But (3.) We cannot know anything of nature but by an analysis of it to its true initial causes: and till we know the first springs of natural motions, we are still but ignorants. These are the alphabet of science, and nature cannot be read without them. Now who dares pretend to have seen the prime motive causes, or to have had a view of nature, while she lay in her simple originals? We know nothing but effects, and those but by our senses. Nor can we judge of their causes, but by proportion to palpable causalities, conceiving them like those within the sensible horizon. Now 'tis no doubt with the considerate, but that the rudiments of nature are very unlike the grosser appearances. Thus in things obvious, there's but little resemblance between the mucous sperm, and the completeed animal. The egg is not like the oviparous production: nor the corrupted muck like the creature that creeps from it. There's but little similitude betwixt a terreous humidity, and plantal germinations; nor do vegetable derivations ordinarily resemble their simple seminalities. So then, since there's so much dissimilitude between cause and effect in the more palpable phenomena, we can expect no less between them, and their invisible efficients. Now had our senses never presented us with those obvious seminal principles of apparent generations, we should never have suspected that a plant or animal could have proceeded from such unlikely materials: much less, can we conceive or determine the uncompounded initials of natural productions, in the total silence of our senses. And though the grand secretary of nature, the miraculous Descartes hath here infinitely out-done all the philosophers that went before him, in giving a particular and analytical account of the universal fabric: yet he intends his principles but for hypotheses, and never pretends that things are really or necessarily, as he hath supposed them: but that they may be admitted pertinently to solve the phenomena, and are convenient supposals for the use of life. Nor can any further account be expected from humanity, but how things possibly may have been made consonantly to sensible nature: but infallibly to determine how they truly were effected, is proper to him only that saw them in the chaos, and fashioned them out of that confused mass. For to say, the principles of nature must needs be such as our philosophy makes them, is to set bounds to omnipotence, and to confine infinite power and wisdom to our shallow models.
(4.) According to the notion of the dogmatist, we know nothing; except we knew all things; and he that pretends to science affects an omniscience. For all things being linked together by an uninterrupted chain of causes; and every single motion owning dependence on such a syndrome of prerequired motors: we can have no true knowledge of any, except we comprehend all, and could distinctly pry into the whole ntethod of causal concatenations. Thus we cannot know the cause of any one motion in a watch, unless we were acquainted with all its motive dependences, and had a distinctive comprehension of the whole mechanical frame. And would we know but the most contemptible plant that grows, almost all things that have a being, must contribute to our knowledge: for, that to the perfect science of anything it's necessary to know all its causes; is both reasonable in itsself, and the sense of the dogmatist. So that, to the knowledge of the poorest simple, we must first know its efficient, the manner, and method of its efformation, and the nature of the plastic. To the comprehending of which, we must have a full prospect into the whole archidoxis of nature's secrets, and the immense profundities of occuit philosophy: in which we know nothing till we completely ken all magnetic, and sympathetic energies, and their most hidden causes. And (2.) If we contemplate a vegetable in its material principle, and look on it as made of earth; we must have the true theory of the nature of that element, or we miserably fail of our scientifical aspirings, and while we can only say, 'tis cold and dry, we are pitiful knowers. But now, to profound into the physics of this heterogeneous mass, to discern the principles of its constitution, and to discover the reason of its diversities, are absolute requisites of the science we aim at. Nor can we tolerably pretend to have those without the knowledge of minerals, the causes and manner of their concretions, and among the rest, the magnet, with its amazing properties. This directs us to the pole, and thence our disquisition is led to the whole system of the heavens: to the knowledge of which, we must know their motions, and the causes, and manner of their rotations, as also the reasons of all the planetary phenomena, and of the comets, their nature, and the causes of all their irregular appearings. To these, the knowledge of the intricate doctrine of motion, the powers, proportions, and laws thereof, is requisite. And thus we are engaged in the objects of geometry and arithmetic; yea the whole mathematics, must be contributary, and to them all nature pays a subsidy. Besides, piants are partly materialed of water, with which they are furnisht either from subterranean fountains, or the clouds. Now to have the true theory of the former, we must trace the nature of the sea, its origin; and hereto its remarkable motions of flux and reflux. This again directs us to the moon, and the rest of the celestial phaseis. The moisture that comes from the clouds is drawn up in vapours: to the scientifical discernment of which, we must know the nature and manner of that action, their suspense in the middle region, the qualities of that place, and the causes and manner of their precipitating thence again: and so the reason of the spherical figure of the drops; the causes of windes, hail, snow, thunder, lightning, with all other igneous appearances, with the whole physiology of meteors must be enquired into. And again (3.) In our disquisition into the formal causes, the knowledge of the nature of colours, is necessary to complete the science. To be informed of this, we must know what light is; and light being effected by a motion on the organs of sense, 'twill be a necessary requisite, to understand the nature of our sensitive faculties, and to them the essence of the soul, and other spiritual subsistences. The manner how it is materially united, and how it is aware of corporeal motion. The seat of sense, and the place where 'tis principally affected: which cannot be known but by the anatomy of our parts, and the knowledge of their mechanical structure. And if further (4.) we contemplate the end of the effect we instanced in, its principal final cause, being the glory of its maker, leads us into divinity; and for its subordinate, as 'tis designed for alimental sustenance to living creatures, and medicinal uses to man, we are conducted into zoography, and the whole body of physic. Thus then, to the knowledge of the most contemptible effect in nature, 'tis necessary to know the whole syntax of causes, and their particular circumstances, and modes of action. Nay, we know nothing, till we know ourselves, which are the summary of all the world without us, and the index of the creation. Nor can we know ourselves without the physiology of corporeal nature, and the metaphysics of souls and angels. So then, every science borrows from all the rest; and we cannot attain any single one, without the encyclopedia. I have been the more diffuse and particular upon this head, because it affords a catalogue of the instances of our ignorance; and therefore though it may seem too largely spoken to in relation to the particular I am treating of, yet 'tis not improper in a more general reference to the subject.