We have difficulty thinking of an idea even when we have all the facts in front of us. Thomas H. Huxley exclaimed after reading On the Origin of Species, "How stupid of me not to have thought of this."

Connecting unrelated ideas needs courage, as most people will cross-connect the related ideas. The ideas that seem very unreasonable at first requires daring, and only afterwards does it seem reasonable. 

Creativity requires isolation. The creative person's mind is mixing information all the time, even if he is not conscious of it. Consider the famous example of Kekule working out the structure of benzene in his sleep.

The presence of others can disrupt this process since creation is embarrassing and messy. Only one out of a thousand foolish ideas are good, and you don't want to display them all.

No two people have the exact mental stores of items. One person may know A but not B, and the other may know B but not A. If both know A and B, they may get the idea, but not simultaneously.

Further, the information may be a combination of A-B, which may not be significant. But if one mentions some unusual combination of A-B and the other of A-C, the combination of A-B-C may give an answer, which neither could find separately.

There must be a sense of comfort, permissiveness and relaxation. Generally, people disapprove of creativity. To be creative in public can be worrisome.

Individuals must feel that other's won't make fun of them. Therefore, people must be willing to sound foolish and listen to others sound foolish.