It's summertime and to counterbalance the kind of light easy reading many people prefer in this season, I recommend two titles that are anything but light or easy. In keeping with the theme of the reading program, both are journeys, be it of a vertical kind -- one through deep time and the other through realms of the spirit. Use the season to exercise your mind and expand your understanding.

The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution by Richard Dawkins

Using a format based on Chaucer's Canterbury Tales, the author traces humanity's ancestral tree all the way back to the beginning of life on earth some 4 billion years ago. Dawkins' pilgrimage consists of 40 tales each one based on a particular organism that has an evolutionary role in the epic story leading up to us. Each tale employs a wealth of detail drawn from fossil evidence, genetics, morphology, and ecology to demonstrate evolutionary principals such as how sexual section in peacocks pertains to our standing upright or how the nervous system of the platypus relates to the mind-body connection in humans. These kinds of apparent digressions take the reader into fascinating side stories before bringing him back into the main flow of the book backwards through time. This thick book, densely but extremely well written and encyclopedic in scope, is science writing at its best, at once authoritative and conversational in style. Your investment of time and effort in Dawkins' magnum opus will be richly rewarded.

The Faith Instinct: How Religion Evolved and Why it Endures by Nicholas Wade

As the subtitle implies, the book attempts to answer two related questions but is really successful only in explaining the former one. The author's perspective is that of evolutionary biology, and religion is therefore the result of natural selection which enhanced the survival of early humans because religious beliefs and rituals promoted group cohesion, cooperation and the like. The author then further maintains that group cohesion and bonding are also why it endures but overlooks the fact that in large developed societies there are a variety of other institutions which have taken over that social function just as he overlooks the value of religion to individuals. That of course would go a long way to explain the latter question but because of the primacy of visionary and other interior states it also points to the difficulty of understanding religion at all. But perhaps I am expecting too much from the book. All in all, the author is writing for the general public and provides a good starting point for going further into what is a strange and very human landscape.