" On the other hand, we can all call to mind the case of seeing the same thing many times over and over. Everyone has had the experience of having their impression of a particular object change depending upon their feelings or conditions at a given moment. This is because the object is seen under the influence of the mental state of that moment. Of course, at the time when we are looking at something, we are generally not aware of the way our feelings are being protected into the situation.
Seen in this way, our so-called cognition, or the action of discerning the meaning of things as they are perceived by us, is never in any case a perception of the external world exactly as it is, but rather a world that can only be apprehended via its interface with our present mental state. In other words, it is nothing other than our own mind that constructs things and determines their content. This is the meaning of "consciousness-only," or "nothing but the transformations of consciousness." And, if we turn this around, we ourselves are nothing other than things that dwell in a world defined by the limits of that which is knowable by the functions of our own mind. "
― , Living Yogācāra: An Introduction to Consciousness-Only Buddhism