It goes without saying that giving a book the title "100 Works of Art That Will Define Our Age" is a hostage to fortune. We lack the necessary perspective when it comes to judging what it is about our time that is most important or representative culture-wise, for which reason the work of drawing up grand lists — the creation of a canon of the moment — is best left to those who come after.
The art world moves so fast these days that such a volume will doubtless seem out of date even before it makes it to paperback (the earliest piece included is Marc Quinn's "Self," from 1991; the most recent is Ai Weiwei's "Sunflower Seeds" from 2010).