All that stock of arguments [the skeptics] produce to depreciate our faculties, and make mankind appear ignorant and low, are drawn principally from this head, to wit, that we are under an invincible blindness as to the true and real nature of things.

Casting an eye on the education of children, from whence I can make a judgment of my own, I observe they are instructed in religious matters before they can reason about them, and consequently that all such instruction is nothing else but filling the tender mind of a child with prejudices.

Few men think, yet all will have opinions.

Doth the Reality of sensible things consist in being perceived? or, is it something distinct from their being perceived, and that bears no relation to the mind?

But, say you, surely there is nothing easier than for me to imagine trees, for instance, in a park [. . .] and nobody by to perceive them. [...] The objects of sense exist only when they are perceived; the trees therefore are in the garden [. . .] no longer than while there is somebody by to perceive them.

That food nourishes, sleep refreshes, and fire warms us; that to sow in the seed-time is the way to reap in the harvest, and, in general, that to obtain such or such ends, such or such means are conducive, all this we know, not by discovering any necessary connexion between our ideas, but only by the observation of the settled laws of nature, without which we should be all in uncertainty and confusion, and a grown man no more know how to manage himself in the affairs of life than an infant just born.

The method of Fluxions is the general key by help whereof the modern mathematicians unlock the secrets of Geometry, and consequently of Nature.