I'm reading Michael Bierut's 79 Short Essays On Design
It's a collection of his essays which have previously appeared in Emigre, Adbusters, I.D. and mostly on his blog Design Observer.
Anyone who saw Michael Bierut in the documentary Helvetica knows that he is both hilarious and really smart. His humour and insightfulness come through loud and clear in these essays which range in topic from art to politics to commentary on revered figures from the 'design pantheon' including Paul Rand and Tibor Kalman.
I really groove with his insistence in the first essay that designers (and illustrators by extension) should push themselves to learn about much more than design. As he states " The more things you're interested in, the better your work will be."