Principles Of Human Knowledge - pg. 55

The first story is interesting. Berkeley supposes that minds are active principles or beings which operate on ideas. How does such a being come to have a conception of itself? The official answer, the best account of which is given in a passage added to the Dialogues, is that the mind, an active being, as such reflects itself to itself. 'The being of myself, that is, my own soul, mind or thinking principle, I evidently know by reflexion' (p. 233). We would do well, of course, to enquire carefully what sort of reflection this might be, and indeed how a mind might be thought capable of reflecting itself to itself (are we supposed to think of a mirror here?). And we should also be interested in the idea that what is reflected is an agent, and that it is in acting that one creates a reflection for oneself. But however all this might be, it is important first to notice the difference between Berkeley's approach here and that of Descartes. For Descartes, I know my own existence because it is impossible for me to doubt it; the proof is an intellectual proof of an intellectual being. For Berkeley, the proof lies not in thought but in agency.