40 (age) is an age where it's rare that you see an artist really contribute something amazing.
40 (age) is a cutoff point for most human achievement. The vitalizing work of the world is done before the age of forty and if one were to subtract the achievements of men above forty, we would practically be where we are today.
40 (age) is when life begins but so do fallen arches, rheumatism, faulty eyesight, and the tendency to tell a story to the same person, three or four times.
40 (age) is a turning point in life. The first forty years of life give us the text... the next thirty supply the commentary.
40 (age) is when we come to know that our friends, who we wanted so much in our 30s, won't save us any more than love did.
40 (age) is the age at when men become like the New York Times Sunday crossword puzzle - tricky, complicated, and you're never really sure you got the right answer.