This is a remarkable account of a journey to the Amazon, where a local variety of psilocybin mushrooms were taken, as well as ayahuasca, the shamanic brew, over a period of weeks. This was no aimless hippytrip just to get high, but an attempt to penetrate the mysteries of time and space. Since Mckenna, and his brother afterwards came up with the notion of the 'TimeWave' and had a computer programme developed from it, their findings are worth tapping into. Though a serious account, there are comic moments, and the author often resorts to his journal of the time, regarding his younger self with a raised eyebrow. If you have ever been in the space he describes, you will understand it all clearly, if you haven't you'll be perturbed and puzzled.