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we find them so often deftroyed by an excefs or defect of the fun's warmth, which an accidental pofition in fome parts of this our little globe exposes them to. The qualities obferved in a loadstone must needs have their fource far beyond the confines of that body; and the ravage made often on feveral forts of animals, by invifible caufes, the certain death (as we are told) of fome of them, by barely paffing the line, or, as it is certain of others, by being removed into a neighbouring country, evidently fhow that the concurrence and operation of feveral bodies, with which they are feldom thought to have any thing to do, is abfolutely neceffary to make them be what they appear to us, and to preferve those qualities by which we know and diftinguish them. We are then quite out of the way, when we think that things contain within themselves the qualities that appear to us in them; and we in vain fearch for that conftitution within the body of a fly, or an elephant, upon which depend thofe qualities and powers we obferve in them; for which, perhaps, to understand them aright, we ought to look not only beyond this our earth and atmosphere, but even beyond the fun, or remoteft ftar our eyes have yet difcovered; for how much the being and operation of particular fubftances in this our globe depend on caufes utterly beyond our view, is impoffible for us to determine. We fee and perceive fome of the motions and groffer operations of things here about us, but whence the streams come that keep all thefe curious machines in motion and repair, how conveyed and modified, is beyond our notice and apprehen fion; and the great parts and wheels, as I may fo fay, of this ftupendous structure of the univerfe, may, for ought we know, have fuch a connection and dependence in their influences and operations one upon another, that perhaps things in this our manfion would put on quite another face, and ceafe to be what they are, if fome one of the fars or great bodies incomprehenfibly remote from us, fhould cease to be or move as it does. This is certain; things, however

abfolute and entire they feem in themselves, are but retainers to other parts of nature, for that which they are most taken notice of by us. Their obfervable qualities, actions, and powers, are owing to fomething without them; and there is not fo complete and perfect a part that we know of nature, which does not owe the being it has, and the excellencies of it, to its neighbours; and we must not confine our thoughts. within the furface of any body, but look a great deal farther, to comprehend perfectly those qualities that are in it.

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Ir this be fo, it is not to be wondered that we have very imperfect ideas of fubftances; and that the real effences, on which depend their properties and operations, are unknown to us. We cannot difcover fo much as that fixe, figure, and texture of their minute and active parts, which is really in them, much lefs the different motions and impulfes made in and upon them by bodies from without, upon which depends, and by which is formed, the greatest and most remarkable part of thofe qualities we obferve in them, and of which our complex ideas of them are made up. This confideration alone is enough to put an end to all our hopes of ever having the ideas of their real effences; which, whilft we want, the nominal effences we make use of instead of them, will be able to furnifh us but very fparingly with any general knowledge, or univerfal propofitions capable of real certainty.

13. Judgment may reach farther, but that is not

Knowledge.

WE are not therefore to wonder, if certainty be to be found in very few general propofitions made concerning fubftances: Our knowledge of their qualities and properties go very feldom farther than our fenfes reach and inform us. Poffibly inquifitive and obferving men may, by ftrength of judgment, penetrate farther, and on probabilities taken from wary obfervation, and hints well laid together, often guefs right at what experience has not yet difcovered to them: But

this is but guefling ftill; it amounts only to opinion, and has not that certainty which is requifite to knowledge; for all general knowledge lies only in our own thoughts, and confifts barely in the contemplation of our own abstract ideas. Wherever we perceive any agreement or disagreement amongst them, there we have general knowledge; and by putting the names of thofe ideas together accordingly in propofitions, can with certainty pronounce general truths. But because the abstract ideas of fubftances, for which their fpecific names ftand, whenever they have any distinct and determinate fignification, have a difcoverable connection or inconfiftency with but a very few other ideas; the certainty of universal propofitions concerning fubStances is very narrow and fcanty in that part, which is our principal inquiry concerning them; and there is fcarce any of the names of fubftances, let the idea it is applied to be what it will, of which we can generally and with certainty pronounce, that it has or has not this or that other quality belonging to it, and conftantly co-existing or inconfiftent with that idea, wherever it is to be found.

§14. What is requifite for our Knowledge of Subftances.

BEFORE We can have any tolerable knowledge of this kind, we muft firft know what changes the primary qualities of one body do regularly produce in the primary qualities of another, and how. Secondly, We muft know what primary qualities of any body produce certain fenfations or ideas in us. This is in truth no lefs than to know all the effects of matter, under its divers modifications of bulk, figure, cohefion of parts, motion, and reft; which, I think, every body will allow is utterly impoffible to be known by us without revelation; nor, if it were revealed to us what fort of figure, bulk, and motion of corpufcles, would produce in us the fenfation of a yellow colour, and what fort of figure, bulk, and texture of parts, in the fuperficies of any body, were fit to give fuch corpufcles their due motion to produce that colour;

75 would that be enough to make univerfal propofitions with certainty, concerning the feveral forts of them, unless we had faculties acute enough to perceive the precife bulk, figure, texture, and motion of bodies in thofe minute parts, by which they operate on our fenfes, that fo we might by those frame our abstract ideas of them. I have mentioned here only corporeal fubftances, whofe operations feem to lie more level to our understandings; for as to the operations of Spirits, both their thinking and moving of bodies, we at first fight find ourselves at a lofs; though perhaps when we have applied our thoughts a little nearer to the confideration of bodies, and their operations, and examined how far our notions, even in thefe, reach, with any clearnefs, beyond fenfible matter of fact, we hall be bound to confefs, that even in these too our difcoveries amount to very little beyond perfect ignorance and incapacity.

§ 15. Whilst our Ideas of Subftances contain not their real Conftitutions, we can make but few general certain Propofitions concerning them. THIS is evident, the abstract complex ideas of fubftances, for which their general names ftand, not comprehending their real conftitutions, can afford us but very little univerfal certainty; because our ideas of them are not made up of that, on which thofe qualities we obferve in them, and would inform ourfelves about, do depend, or with which they have any certain connection: v. g. Let the idea to which we give the name man, be, as it commonly is, a body of the ordinary shape, with fenfe, voluntary motion, and reafon joined to it: This being the abstract idea, and confequently the effence of our fpecies man, we can make but very few general certain propofitions concerning man, ftanding for fuch an idea; because, not knowing the real conftitution on which fenfation, power of motion, and reasoning, with that peculiar fhape, depend, and whereby they are united together in the fame fubject, there are very few other qualities, with which we can perceive them to have a neceffary connection; and therefore we can

not with certainty affirm, that all men fleep by intervals; that no man can be nourished by word or Alones; that all men will be poifned by bemlock; because these ideas have no connection nor repugnancy with this our nominal effence of man, with this abftract idea that name ftands for. We must in thefe and the like appeal to trial in particular fubjects, which can reach but a little way; we must content ourfelves with probability in the reft, but can have no general certainty, whilft our specific idea of man contains not that real conftitution, which is the root, wherein all his infeparable qualities are united, and from whence they flow. Whilft our idea, the word man stands for, is only an imperfect collection of fome fenfible qualities and powers in him, there is no difcernible connection or repugnance between our specific idea, and the operation of either the parts of hemlock or ftones upon his conftitution. There are animals that fafely eat hemlock, and others that are nourished by wood and ftones: But as long as we want ideas of thofe real conftitutions of different forts of animals, whereon these and the like qualities and powers depend, we must not hope to reach certainty in univerfal propofitions concerning them. Thofe few ideas only which have a difcernible connection with our nominal ellence, or any part of it, can afford us fuch propofitions; but thefe are fo few, and of fo little moment, that we may jufly look on our certain general knowledge of fubftances as almost none at all.

16. Wherein lies the general Certainty of Pro

pofitions.

To conclude, general prop:fitions, of what kind soever, are then only capable of certainty, when the terms used in them ftand for fuch ideas, whose agreement or disagreement, as there exprefled, is capable to be discovered by us; and we are then certain of their truth or falfehood, when we perceive the ideas the terms ftand for, to agree or not agree, according as they are affirmed or denied one of another; whence we may take notice, that general certainty is never to

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