All scientific knowledge to which man owes his role as master of the world arose from playful activities.

Natural selection does not give any preference at all to anything that, in the long run, could be advantageous for the species but blindly rewards everything that, momentarily, affords greater procreative success.

I believe that both art and the human striving for cognitive comprehension are manifest forms of the grand game in which nothing more is stipulated than the game's rules; both art and actively solicited perceptions are but special cases of the recurring creative act to which we owe our existence.

Barking dogs may occasionally bite, but laughing men hardly ever shoot!

Every mutation through a new combination of genetic factors that provides the organism with a new opportunity for coming to terms with the conditions of its environment signifies no more and no less than that new information about this environment has got into that organic system. Adaptation is essentially a cognitive process.

If you confine yourself to this Skinnerian technique, you study nothing but the learning apparatus and you leave out everything that is different in octopi, crustaceans, insects and vertebrates. In other words, you leave out everything that makes a pigeon a pigeon, a rat a rat, a man a man, and, above all, a healthy man healthy and a sick man sick.

I have found the missing link between the higher ape and civilized man; it is we.