You only need to read Charlie's last heartwrenching words at the end of this novel, when he has lost his intelligence and is now even more intellectually challenged than he was at the beginning of the novel. Note what he says on the final page when he writes to "Miss Kinnian":
If you ever reed this Miss Kinnian dont be sorry for me. Im glad I got a second chanse in life like you said to be smart because I lerned alot of things that I never even new were in this werld and Im grateful I saw it all even for a littel bit. And Im glad I found out all about my family and me. It was like I never had a family til I remembird abotu them and saw them and now I know I had a family and I was a person just like evryone.
From Charlie's perspective, even though his fate at the end of this tragic, thought-provoking novel is truly sad, he is glad he has sought truth, and believes that the truth he has gained has been worth the price of his slip back into a state marked by a lack of intelligence. In patricular, Charlie sights not just the scientific discoveries he has made, but also the personal discoveries he has made about his family as being worthwhile, even though they have actually caused him pain.