A Vulgar Mechanick can ...

A Vulgar Mechanick can practice what he has been taught or seen done, but if he is in an error he knows not how to find it out and correct it, and if you put him out of his road he is at a stand. Whereas he that is able to reason nimbly and judiciously about figure, force, and motion, is never at rest till he gets over every rub. (from a letter dated 25 May, 1694)
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 Isaac Newton

Quotes from the same author

Philosophy is such an impertinently litigious lady that a man had as good be engaged in lawsuits as have to do with her.
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 Isaac Newton
Now the smallest Particles of Matter may cohere by the strongest Attractions, and compose bigger Particles of weaker Virture.... There are therefore Agents in Nature able to make the Particles of Bodies stick together by very strong Attraction. And it is the Business of experimental Philosophy to find them out.
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 Isaac Newton
God is able to create particles of matter of several sizes and figures and perhaps of different densities and forces, and thereby to vary the laws of nature, and make worlds of several sorts in several parts of the Universe.
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 Isaac Newton
God who gave Animals self motion beyond our understanding is without doubt able to implant other principles of motion in bodies [which] we may understand as little. Some would readily grant this may be a Spiritual one; yet a mechanical one might be showne, did not I think it better to pass it by.
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 Isaac Newton
It seems probable to me that God, in the beginning, formed matter in solid, massy, hard, impenetrable, moveable particles, of such sizes and figures, and with such other properties, and in such proportions to space, as most conduced to the end for which He formed them; and that these primitive particles, being solids, are incomparably harder than any porous bodies compounded of them, even so very hard as never to wear or break in pieces; no ordinary power being able to divide what God had made one in the first creation.
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 Isaac Newton