Meditations on First Philosophy
Initially, a very thought-provoking read. Descartes begins by rejecting all his previously held beliefs derived from the senses, and sets out on a mission to discover what we can establish as true, or if there is such a thing as truth at all. He even questions his own existence! This is where cogito, ergo sum appears (I think, therefore I am)—a thinking entity must exist to do the thinking.
After this is where I start to take issue. He moves to the existence of God, and ultimately concludes that God DOES exist, since our imperfect and limited human brains could not conceive of something all-powerful, unless this idea was planted in us by that all-powerful being to begin with. After this, he moves to explain how God is benevolent. My thoughts on this are here...
Ultimately I'm left disappointed. Still recommend, because the idea of buliding up objective truths from nothing is quite interesting and challenging, but Descartes' decision to explain away his doubts using God is weak.