Whether the powers are distinguished by their acts and objects?

Objections

Objection 1 : It would seem that the powers of the soul are not distinguished by acts and objects. For nothing is determined to its species by what is subsequent and extrinsic to it. But the act is subsequent to the power; and the object is extrinsic to it. Therefore the soul's powers are not specifically distinct by acts and objects.
Objection 2 : Further, contraries are what differ most from each other. Therefore if the powers are distinguished by their objects, it follows that the same power could not have contrary objects. This is clearly false in almost all the powers; for the power of vision extends to white and black, and the power to taste to sweet and bitter.
Objection 3 : Further, if the cause be removed, the effect is removed. Hence if the difference of powers came from the difference of objects, the same object would not come under different powers. This is clearly false; for the same thing is known by the cognitive power, and desired by the appetitive.
Objection 4 : Further, that which of itself is the cause of anything, is the cause thereof, wherever it is. But various objects which belong to various powers, belong also to some one power; as sound and color belong to sight and hearing, which are different powers, yet they come under the one power of common sense. Therefore the powers are not distinguished according to the difference of their objects.