"These cards evolved from our separate observations of the principles underlying what we are doing. Sometimes they were recognized in retrospect (intellect catching up with intuition), sometimes they were identified as they were happening, sometimes they were formulated. They can be used as a pack (a set of posibilities being continuously reviewed in the mind) or by drawing a single card from a shuffled pack when a dilemma occurs in a working situation. In this case the card is trusted even if it appropriateness is quite unclear. They are not final, as new ideas will present themselves, and others will become self-evident."