Science fiction is more often a reflection of existing societal trends than a prediction of trends to come. The upsurge in drug use is precisely mirrored by the upsurge in the use of such themes in science fiction. Science fiction is as much a guide to where we are as it is a vision of where we are going. A literature so popular with the young, commanding so intense and devoted a following, can be of significant value in revealing the patterns contemporary society is taking and will take in the years just ahead. - Summary by Robert Silverberg, from Introduction