But the velocities of the velocities - the second, third, fourth, and fifth velocities, etc. - exceed, if I mistake not, all human understanding.

This perceiving, active being is what I call mind, spirit, soul, or myself. By which words I do not denote any one of my ideas, but a thing entirely distinct from them, wherein they exist, or, which is the same thing, whereby they are perceived; for the existence of an idea consists in being perceived.

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 table I write on I say exists ... meaning thereby that if I was in my study I might perceive it, or that some other spirit actually does perceive it.

To me it seems that liberty and virtue were made for each other. If any man wish to enslave his country, nothing is a fitter preparative than vice; and nothing leads to vice so surely as irreligion.

The most ingenious men are now agreed, that [universities] are only nurseries of prejudice, corruption, barbarism, and pedantry.

To be is to be perceived (Esse est percipi)." Or, "If a tree falls in the forest and no one is there to hear it, does it make a sound?