The Future of the Body is what I would consider a “modern classic.”
It is one of the truly comprehensive texts published on modern consciousness and transformative studies. I can't recommend it enough as mandatory reading for any student in the field of consciousness, transpersonal, and transformative psychology (or any field directly related to human potentials). However, my only reservation is that there is virtually no mention of psychoactives, those taboos of human culture, within the text as a whole. This fact alone keeps it from being truly comprehensive in terms of transformative capacities and forms of transcendence as defined by leaders in the field such as Susanne Cook-Greuter and even Ken Wilber (though I recognize his lack of attendance to this issue). Despite this omission, this text is, in my opinion, required reading for all students of consciousness-related studies.

It is difficult to estimate how many extraordinary attributes are available to us, given our general ignorance today about the further reaches of human nature.  We do not know how many human potentials are neglected or suppressed in this (and every) culture.  But it would not be difficult, I believe, to enlarge the inventories … 

However, given the ancient witness to contemplative knowing and the great abundance of evidence for psi phenomena, many sources of which I cite in subsequent chapters, it is a great mistake to exclude such things from our accounts of human nature.  That is why many, if not most, great thinkers since antiquity have given paranormal events and mystical truth claims a central place in their philosophies.