tant objects, the transmission of impressions from spirit to spirit, no less than from body to body, and the like.

32. From the foregoing remarks, it is clear that the five last species of instances (the similar, singular, deviating, and bordering instances, and those of power) should not be reserved for the investigation of any given nature, as the preceding and many of the succeeding instances must, but a collection of them should be made at once, in the style of a particular history; so that they may arrange the matter which enters the understanding, and correct its depraved habit, for it is necessarily imbued, corrupted, perverted, and distorted by daily and habitual impressions.

They are to be used, therefore, as a preparative, for the purpose of rectifying and purifying the understanding, for, whatever withdraws it from habit, levels and planes down its surface for the reception of the dry and pure light of true notions. These instances, moreover, level and prepare the way for the operative branch, as we will mention in its proper place, when speaking of the practical deductions.

33. In the eleventh rank of prerogative instances, we will place accompanying and hostile instances. These are such as exhibit any body or concrete, where the required nature is constantly found, as an inseparable companion, or, on the contrary, where the required nature is constantly avoided and excluded from attendance, as an enemy. From these instances may be formed certain and universal propositions, either affirmative or negative; the subject of which will be the concrete body, and the predicate the required nature. For particular propositions are by no means fixed, when the required nature is found to fluctuate and change in the concrete, either approaching and acquired, or receding and laid aside. Hence, particular propositions have no great prerogative, except in the case of migration, of which we have spoken above. Yet such particular propositions are of great use, when compared with the universal, as will be mentioned in its proper place. Nor do we require absolute affirmation or negation, even in universal propositions, for, if the exceptions be singular or rare, it is sufficient for our purpose.

The use of accompanying instances is to narrow the affirmative of form. For, as it is narrowed by the migrating instances, where the form must necessarily be something communicated or destroyed by the act of migration, so it is narrowed by accompanying instances, where the form must necessarily be something which enters into the concretion of the body, or, on the contrary, is repugnant to it, and one who is well acquainted with the constitution or formation of the body, will not be far from bringing to light the form of the required nature.

For example: let the required nature be heat.

For, in

Flame is an accompanying instance. water, air, stone, metal, and many other substances, heat is variable, and can approach or retire, but all flame is hot, so that heat always accompanies the concretion of flame. We have no hostile instance of heat. For the senses are unacquainted with the interior of the earth, and there is no concretion of any known body which is not susceptible of heat.

Again, let solidity be the required nature. Air is a hostile instance. For metals may be liquid or solid, so may glass; even water may become solid by congelation, but air cannot become solid or lose its fluidity.

With regard to these instances of fixed propositions, there are two points to be observed, which are of importance. First, that if there be no universal affirmative or negative, it be carefully noted as not existing. Thus, in heat, we have observed that there exists no universal negative, in such substances at least as have come to our knowledge. Again, if the required nature be eternity or incorruptibility, we have no universal affirmative within our sphere, for these qualities cannot be predicated of any bodies below the heavens, or above the interior of the earth. Secondly, To our general propositions as to any concrete, whether affirmative or negative, we should subjoin the concretes which appear to approach nearest to the non-existing substances; such as the most gentle or least burning flames in heat, or gold in incorruptibility, since it approaches nearest to it. For they all serve to show the limit of existence and non-existence, and circumscribe forms, so that they cannot wander beyond the conditions of matter.

34. In the twelfth rank of prerogative instances, we will class those subjunctive instances, of which we spoke in the last aphorism, and which we are also wont to call instances of extremity or limits; for they are not only serviceable when subjoined to fixed propositions, but also of themselves and from their own nature. They indicate with sufficient precision the real divisions of nature, and measures of things, and the "how far" nature effects or allows of any thing, and her passage thence to something else. Such are gold in weight, iron in hardness, the whale in the size of animals, the dog in smell, the flame of gunpowder in rapid expansion, and others of the like nature. Nor are we to pass over the extremes in defect as well as in abundance, as spirits of wine in weight, the touchstone in softness, the worms upon the skin in the size of animals, and the like.

35. In the thirteenth rank of prerogative instances, we will place those of alliance or union. They are such as mingle and unite natures held to be heterogeneous, and observed and marked as such in received classifications.

These instances show that the operation and

effect, which is considered peculiar to some one of such heterogeneous natures, may also be attributed to another nature styled heterogeneous; so as to prove that the difference of the natures is not real nor essential, but a mere modification of a common nature. They are very serviceable, therefore, in elevating and carrying on the mind from differences to genera, and in removing those phantoms and images of things, which meet it in disguise in concrete substances.

For example; let the required nature be heat. The classification of heat into three kinds, that of the celestial bodies, that of animals, and that of fire, appears to be settled and admitted: and these kinds of heat, especially one of them compared with the other two, are supposed to be different, and clearly heterogeneous in their essence and species, or specific nature; since the heat of the heavenly bodies and of animals generates and cherishes, whilst that of fire corrupts and destroys. We have an instance of alliance then in a very common experiment, that of a vine branch admitted into a building where there is a constant fire, by which the grapes ripen a whole month sooner than in the air; so that fruit upon the tree can be ripened by fire, although this appear the peculiar effect of the sun. From this beginning, therefore, the understanding rejects all essential difference, and easily ascends to the investigation of the real differences between the heat of the sun and that of fire, by which their operation is rendered dissimilar, although they partake of a

eommon nature.

These differences will be found to be four in number. The heat of the sun is much milder and gentler in degree than that of fire. 2. It is much more moist in quality, especially as it is transmitted to us through the air. 3. Which is the chief point, it is very unequal, advancing and increased at one time, retiring and diminished at another; which mainly contributes to the generation of bodies. For Aristotle rightly asserted, that the principal cause of generation and corruption on the surface of the earth, was the oblique path of the sun in the zodiac, whence its heat becomes very unequal, partly from the alternation of night and day, partly from the succession of summer and winter. Yet must he immediately corrupt and prevent his discovery, by dictating to nature according to his habit, and dogmatically assigning the cause of generation to the approach of the sun and that of corruption to its retreat; whilst in fact each circumstance indifferently and not respectively contributes both to generation and corruption; for unequal heat tends to generate and corrupt, as equable heat does to preserve. 4. The fourth difference between the heat of the sun and fire is of great consequence; namely, that the sun, gradually, and for a length of time, insinuates its effects, whilst those of fire (urged by the impatience of man) are brought to a

termination in a shorter space of time. But if any one were to pay attention to the tempering of fire, and reducing it to a more moderate and gentle degree, (which may be done in various ways,) and then were to sprinkle and mix a degree of humidity with it, and above all were to imitate the sun in its inequality, and lastly were patiently to suffer some delay, (not such, however, as is proportioned to the effects of the sun, but more than men usually admit of in those of fire,) he would soon banish the notion of any difference, and would attempt, or equal, or perhaps sometimes surpass the effect of the sun, by the heat of fire. A like instance of alliance is that of reviving butterflies, benumbed and nearly dead from cold, by the gentle warmth of fire, so that fire is no less able to revive animals than to ripen vegetables. We may also mention the celebrated invention of Fracastorius, of applying a pan considerably heated to the head in desperate cases of apoplexy, which clearly expands the animal spirits, when compressed and almost extinguished by the humours and obstructions of the brain, and excites them to action, as the fire would operate on water or air, and in the result produces life. Eggs are sometimes hatched by the heat of fire, an exact imitation of animal heat; and there are many instances of the like nature, so that no one can doubt that the heat of fire, in many cases, can be modified till it resemble that of the heavenly bodies and of animals.

Again, let the required natures be motion and rest. There appears to be a settled classification, grounded on the deepest philosophy, that natural bodies either revolve, move in a straight line, or stand still and rest. For there is either motion without limit, or continuance within a certain limit, or a translation towards a certain limit. The eternal motion of revolution appears peculiar to the heavenly bodies, rest to this our globe, and the other bodies (heavy and light, as they are termed, that is to say, placed out of their natural position) are borne in a straight line to masses or aggregates which resemble them, the light towards the heaven, the heavy towards the earth and all this is very fine language.

But we have an instance of alliance in low comets, which revolve, though far below the heavens; and the fiction of Aristotle, of the comet being fixed to or necessarily following some star, has been long since exploded; not only because it is improbable in itself, but from the evident fact of the discursive and irregular motion of comets, through various parts of the heavens.

Another instance of alliance is that of the motion of air, which appears to revolve from east to west within the tropics, where the circles of revolution are the greatest.

The flow and ebb of the sea would perhaps be another instance, if the water were once found to

have a motion of revolution, though slow and hardly perceptible, from east to west, subject, however, to a reaction twice a day. If this be so, it is clear that the motion of revolution is not confined to the celestial bodies, but is shared also by air and water.

Again; the supposed peculiar disposition of light bodies to rise, is rather shaken; and here we may find an instance of alliance in a water bubble. For if air be placed under water, it rises rapidly towards the surface, by that striking motion (as Democritus terms it) with which the descending water strikes the air, and raises it; not by any struggle or effort of the air itself: and when it has reached the surface of the water, it is prevented from ascending any further, by the slight resistance it meets with in the water, which does not allow an immediate separation of its parts, so that the tendency of the air to rise must be very slight.

Again; let the required nature be weight. It is certainly a received classification, that dense and solid bodies are borne towards the centre of the earth, and rare and light bodies to the circumference of the heavens, as their appropriate places. As far as relates to places, (though these things have much weight in the schools,) the notion of there being any determinate place is absurd and puerile. Philosophers trifle, therefore, when they tell you that if the earth were perforated, heavy bodies would stop on their arrival at the centre. This centre would indeed be an efficacious nothing or mathematical point, could it affect bodies or be sought by them, for a body is not acted upon except by a body.* In fact, this tendency to ascend and descend, is either in the conformation of the moving body, or in its harmony and sympathy with another body. But if any dense and solid body be found, which does not however, tend towards the earth, the classification is at an end. Now, if we allow of Gilbert's opinion, that the magnetic power of the earth, in attracting heavy bodies, is not extended beyond the limit of its peculiar virtue, (which operates always at a fixed distance and no further,)† and this be proved by some instance, such an instance will be one of alliance in our present subject. The nearest approach to it is that of waterspouts, frequently seen by persons navigating the Atlantic towards either of the Indies. For the force and mass of the water suddenly effused by waterspouts, appears to be so considerable, that the water must have been collected previously, and have remained fixed where it was formed, until it was afterwards forced down by some violent

*But see Bacon's own corollary at the end of the instances

of divorce, Aphorism 37.

+ Since Newton's discovery of the law of gravitation, we find that the attractive force of the earth must extend to an Infinite distance. Bacon himself alludes to the operation of this attractive force at great distances, in the instances of the rod. Aphorism 45.

cause, rather than made to fall by the natural m tion of gravity: so that it may be conjecturcă, that a dense and compact mass, at a great distance from the earth, may be suspended as the earth itself is, and would not fall unless forced down. We do not, however, affirm this as certain. In the mean while, both in this respect and many others, it will readily be seen how deficient we are in natural history, since we are forced to have recourse to suppositions for examples, instead of ascertained instances.

Again; let the required nature be the discur sive power of the mind. The classification of human reason, and animal instinct, appears to be perfectly correct. Yet there are some instances of the actions of brutes, which seem to show that they too can syllogize. Thus it is related, that a crow, which had nearly perished from thirst in a great drought, saw some water in the hollow trunk of a tree, but as it was too narrow for him to get into it, he continued to throw in pebbles, which made the water rise till he could drink, and it afterwards became a proverb.

Again; let the required nature be vision. The classification appears real and certain, which considers light as that which is originally visible, and confers the power of seeing; and colour as being secondarily visible, and not capable of being seen without light, so as to appear a mere image or modification of light. Yet there are instances of alliance in each respect; as in snow when in great quantities, and in the flame of sulphur; the one being a colour originally and in itself light, the other a light verging towards a colour.*

36. In the fourteenth rank of prerogative instances, we will place the instances of the cross, borrowing our metaphor from the crosses erected where two roads meet, to point out the different directions. We are wont also to call them decisive and judicial instances, and in some cases instances of the oracle, and of command. Their nature is as follows. When in investigating any nature the understanding is, as it were, balanced, and uncertain to which of two or more natures the cause of the required nature should be assigned, on account of the frequent and usual concurrence of several natures; the instances of the cross show that the union of one nature with the required nature is firm and indissoluble, whilst that of the other is unsteady and separable; by which means the question is decided, and the first is received as the cause, whilst the other is dismissed and rejected. Such instances therefore afford great light, and are of great weight, so that the course of interpretation sometimes terminates and is completed in them. Sometimes, however, they are found amongst the instances already observed, but they are generally new, being ex

Snow reflects light, but is not a source of light.