For passions as defined by him are "perceptions, or feelings, or disturbances of the soul, which are referred to the soul as species, and which (mark the expression) are produced, preserved, and strengthened through some movement of the spirits." (Passions de l'ame, I.27).

But, seeing that we can join any motion of the gland, or consequently of the spirits, to any volition, the determination of the will depends entirely on our own powers; if, therefore, we determine our will with sure and firm decisions in the direction to which we wish our actions to tend, and associate the motions of the passions which we wish to acquire with the said decisions, we shall acquire an absolute dominion over our passions.

Such is the doctrine of this illustrious philosopher (in so far as I gather it from his own words); it is one which, had it been less ingenious, I could hardly believe to have proceeded from so great a man.

Indeed, I am lost in wonder, that a philosopher, who had stoutly asserted, that he would draw no conclusions which do not follow from self--evident premisses, and would affirm nothing which he did not clearly and distinctly perceive, and who had so often taken to task the scholastics for wishing to explain obscurities through occult qualities, could maintain a hypothesis, beside which occult qualities are commonplace.

What does he understand, I ask, by the union of the mind and the body?
What clear and distinct conception has he got of thought in most intimate union with a certain particle of extended matter?
Truly I should like him to explain this union through its proximate cause.