Our internal experience shows immediately that sense cognition is not limited to the mere sensation of colors, sounds, odors, etc. For instance, I am aware that I possess an internal image of the Golden Gate Bridge, even if I am not there, and I remember things that happened yesterday.
The animal should apprehend a thing not only at the actual time of sensation, but also when it is absent. Otherwise, since animal motion and action follow apprehension, an animal would not be moved to seek something absent….ST I, 78, 4.
To explain experiences of this kind, we must refer to the internal senses. The internal senses include: