My third maxim was to endeavor always to conquer myself rather than fortune, and to change my desires rather than the order of the world, and in general to accustom myself to the persuasion that except our own thoughts, there is nothing absolutely in our power; [...] since our will naturally seeks those objects alone which the understanding represents as in some way possible of attainment, it is plain that if we consider all external goods as equally beyond our power, we shall no more regret the absence of such goods as seem due to our birth [...] than our not possessing the kingdoms of China or Mexico [...]. But I confess there is need of prolonged discipline and frequently repeated meditation to accustom the mind to view all objects in this light [...].

—René Descartes, Discourse on Method

Nagel once claimed that it is psychologically impossible to believe the Reductionist View [of personal identity: that mind/brain states do not naturally group together into an objectively distinct “self” or “ego”]. Buddha claimed that, though it is very hard, it is possible. I find Buddha’s claim to be true. After reviewing my arguments, I find that, at the reflective or intellectual level, though it is very hard to believe the Reductionist View, this is possible. [...] Since I can believe this view, I assume that others can do so too. We can believe the truth about ourselves.

—Derek Parfit, Reasons and Persons (p280)