 By “thinking” you may mean that you understand and will and imagine and have sensations, and that you think in such a way that you can contemplate and consider your thought by a reflexive act. This would mean that when you think, you know and consider that you are thinking (and this is really what it is to be conscious [conscius esse] and to have conscious awareness [conscientia] of some activity). Such consciousness, you claim, is a property of a faculty or thing that is superior to matter and is wholly spiritual, and it is in this sense that you are a mind or a spirit. (CSM II 364 / AT VII 533–534)