be conscious

References in classic literature ?
There are various problems as to how we can be conscious now of what no longer exists.
You may be conscious of a friend either by seeing him or by "thinking" of him; and by "thought" you can be conscious of objects which cannot be seen, such as the human race, or physiology.
Unless we are to acquiesce in the view that we can never be conscious of anything outside our own minds, we must say that the object of consciousness need not be mental, though the consciousness must be.
Looking fixedly eastward he seemed to be conscious of some faint lightening in the sky.
Her presence and her touch upon his breast or face would often stop this, and then they learned to expect that he would for some time remain still, with his eyes closed, and that he would be conscious on opening them.