To be inserted in Vol. I. page 282. line ult. after these words (any idea of power.) be∣ginning a new paragraph.
SOME have asserted, that we feel an energy, or power, in our own mind; and Page 299 that having in this manner acquir'd the idea of power, we transfer that quality to matter, where we are not able immediately to disco∣ver it. The motions of our body, and the thoughts and sentiments of our mind, (say they) obey the will; nor do we seek any far∣ther to acquire a just notion of force or power. But to convince us how fallacious this rea∣soning is, we need only consider, that the will being here consider'd as a cause, has no more a discoverable connexion with its effects, than any material cause has with its proper effect. So far from perceiving the connexion betwixt an act of volition, and a motion of the body; 'tis allow'd that no effect is more inexplicable from the powers and essence of thought and matter. Nor is the empire of the will over our mind more intelligible. The effect is there distinguishable and sepa∣rable from the cause, and cou'd not be fore∣seen without the experience of their constant conjunction. We have command over our mind to a certain degree, but beyond that lose all empire over it: And 'tis evidently impossible to fix any precise bounds to our authority, where we consult not experience. In short, the actions of the mind are, in this respect, the same with those of matter. We perceive only their constant conjunction; nor Page 300 can we ever reason beyond it. No internal impression has an apparent energy, more than external objects have. Since, therefore, matter is confess'd by philosophers to operate by an unknown force, we shou'd in vain hope to attain an idea of force by consulting our own minds a.