How would you like to have a disc set in the middle of your forehead which glowed pink whenever you felt sexually aroused? This is the basis of Brian Aldiss' amazingly funny and original novel, first published in 1961 and set in a near-future Britain where the discs are to be made compulsory - but not before a lot of hilarious and even frightening events occur, suggesting that perhaps it's not such a good idea to wear one's, er, 'heart' on one's forehead.