To buy books would be a good thing if we also could buy the time to read them. -- Arthur Schopenhauer
But I like the version of it quoted by Gerrie Lim, who credits Warren Zevon with this rephrasing of Schopenhauer:
We love to buy books because we believe we're buying the time to read them.
Which sums up how I felt when my kids were young and time was terribly precious -- I just had to keep buying books....