It is a different and independent thing, and the character of the mental act only determines how much of the object is apprehended and in what form.
Thus we have to recognize that a thing as perceived contains besides sensory elements other elements present to the mind only in ideal form.
Practical acts are such as, through the medium of our bodily movements, alter the object or its relation to ourselves or to other subjects.
In the act of perception there are accordingly these two things, the mind engaged in a certain act, and the thing called the tree which is not mental.