The 41st Article

What is the power of the soul in respect of the body.

But the will is so free by nature that it can never be constrained. And of two sorts of thoughts which I have distinguished in the soul, whereof some are her actions, to wit her wills; others, her passions, taking that word in its general signification, which comprehends all forms of apprehensions. The first are absolutely in her own power, and cannot, but indirectly, be changed by the body; as on the contrary, the last depend absolutely upon the actions which produce them, and they cannot, unless indirectly, be changed by the soul, except then when her self is the cause of them. And all the action of the soul consists in this, that she merely by willing anything can make the little kernel, whereunto she is strictly joined, move in the manner requisite to produce the effect relating to this will.