Ken Wilber is a contemporary psychologist/philosopher who has authored about 25 books that weave together wisdom of the ages into something he calls Integral Theory. The core of "Integral Theory" is expressed in the suggestion that whatever the question, the answer must consider, "all quadrants, all levels, all lines" of reality.

ALL QUADRANTS sugggests that we would do well to see all phenomena from their exteriors and interiors, individual and social aspects.

The ALL LEVELS aspect posits that human development unfolds in waves that go beyond Piaget's developmental levels, and that only by navigating these waves can we both develop a healthy sense of individuality and transcend (and include) our small-s self in a broader, transpersonal consciousness, our "large-s" Self.

ALL LINES: As the proponents of theories of multiple intelligences have taught us, humans develop along multiple lines. these lines include altruism, cognition, creativity, empathy, kinesthetic skills, meditative states, morals, psychosexuality, worldviews, and many others. Wilber incorporates this wisdom into Integral Theory, noting that, in each of these lines, our development unfolds in stages through each of the four quadrants.

Wilber encourages his students to identify their own developmental lines and to use an integrated mind/body/spirit practice to advance along them.

(description provided by Meetup group member Tom Goddard, The Integral Company)