On paper, this book should be a zero star for someone like me. As people know, I'm a militant atheist, materialist, Marxist, and I wear my politics and philosophy on my sleeve - sometimes even on other peoples' sleeves. And Berkeley is basically the stark opposite of me: a Christian, immaterialists, who undoubtedly held conservative views. Nonetheless, Berkeley was unequivocally a philosophical gangster in the streets, and a freak in the bed.
Seriously though, Berkeley gives every materialist, in his time, hitherto, a run for their money. As the introduction essays remarks, Lenin, and Engels, recognized Berkeley's philosophy was not easy to transcend. And anyone who has read Engels's attempt to transcend it (I have not read Lenin's), knows he failed. According to my friend, Lenin failed too. For Berkeley only two things exist, minds/spirits, and ideas. Well God too, but his argument in favor of God's existence ultimately boils down to: atheist are repugnant, hallelujah.
Despite the extreme advances made in the cognitive sciences, and philosophy overall, returning to the empiricist tradition is always a treat. The writing is clear, the philosophy is simple, and their epistemological system is completely summarizable. Berkeley is no exception. He sets out to rid the world of abstractions, and abstract ideas, especially Platonic forms. Moreover, he wants to make necessary advancements upon Locke's philosophy of primary qualities (i.e., substance, extension, etc), and secondary qualities.
Locke believed when we perceived an object, we perceived secondary qualities, that is qualities that only exist for our mind, such as colors, sounds, tasted, etc.; and primary qualities, which existed independent of observation (e.g., extension, substance). Thus, a table tastes oaky to the human, but delicious to the termite. But to both creatures, the table is extended, and contains substance (the metaphysical glue holding the table together), or matter for the materialist. Berkeley points out that for an empiricist this is a complete contradiction. The empiricist never observes primary qualities, and it is impossible for these qualities to exist outside perception, because how could someone perceive of something existing outside perception? This is a complete contradiction.
If things only exist when they're being perceived, we are left flummoxed. Why is it that things always seems to be where we left them, and that there is consistency and order in the universe? Berkeley believes that there are natural laws, laws that unlike our perception have a will or volition of their own. Moreover, these objects remain consistent because there is one all eternal perceiver: GOD. In the first essay there is no serious argument for why God exist; only that atheist are repugnant beings, worthy of contempt. But isn't Berkeley's philosophy all the more fun when a God doesn't exist? I mean really, the fact that things don't exist when I don't perceive them, and I bring things into existence by viewing them, is substantially more interesting. Moreover, despite the fact that Berkeley says we perceive God in his work, he is essentially using God as the primary quality he rejects.
Overall, great book.