Dagan

“Guilford concluded that creative individuals were also far more likely to exhibit "divergent" rather than "convergent" thinking:

In tests of convergent thinking there is almost always one conclusion or answer that is regarded as unique, and thinking is to be channeled or controlled in the direction of that answer....In divergent thinking, on the other hand, there is much searching about or going off in various directions. This is most obviously seen when there is no unique conclusion. Divergent thinking...is characterized...as being less goal-bound. There is freedom to go off in different directions....Rejecting the old solution and striking out in some direction is necessary, and the resourceful organism will more probably succeed.”
― Kay Redfield Jamison, Touched with Fire: Manic-Depressive Illness and the Artistic Temperament

“The emphasis on shifting essences, uncertainty, and fiercely contrasting opposite states was, of course, neither new nor unique to Byron. He and the other Romantic poets, however, took the ideas and emotions to a particularly intense extreme. Shelley's belief that poetry "marries exultation and horror, grief and pleasure, eternity and change," and that it "subdues to union, under its light yoke, all irreconcilable things," was in sympathy not only with the views of Byron but those of Keats as well. "Negative capability," wrote Keats, exists "when a man is capable of being in uncertainties, Mysteries, doubts, without any irritable reaching out after fact & reason." The "poetical Character," he said:

has no self-it is every thing and nothing-It has no character-it enjoys light and shade; it lives in gusto, be it foul or fair, high or low, rich or poor, mean or elevated-It has as much delight in conceiving an Iago as an Imogen. What shocks the virtuous philosopher, delights the camelion Poet. It does no harm from its relish of the dark side of things any more than from its taste for the bright one; because they both end in speculation.”
― Kay Redfield Jamison, Touched with Fire: Manic-Depressive Illness and the Artistic Temperament

“Psychologist J.P. Guilford, who carried out a long series of systematic psychological studies into the nature of creativity, found that several factors were involved in creative thinking; many of these, as we shall see, relate directly to the cognitive changes that take place during mild manias as well. Fluency of thinking, as defined by Guilford, is made up of several related and empirically derived concepts, measured by specific tasks: word fluency, the ability to produce words each, for example, containing a specific letter or combination of letters; associational fluency, the production of as many synonyms as possible for a given word in a limited amount of time; expressional fluency, the production and rapid juxtaposition of phrases or sentences; and ideational fluency, the ability to produce ideas to fulfill certain requirements in a limited amount of time. In addition to fluency of thinking, Guilford developed two other important concepts for the study of creative thought: spontaneous flexibility, the ability and disposition to produce a great variety of ideas, with freedom to switch from category to category; and adaptive flexibility, the ability to come up with unusual types of solutions to set problems.”
― Kay Redfield Jamison, Touched with Fire: Manic-Depressive Illness and the Artistic Temperament

“(It is of no little interest and irony that Francis Galton, a cousin of Charles Darwin and proponent of selective breeding in humans in order to obtain a "highly gifted race of man," was himself subject to "nervous breakdowns"; he was also appreciative of the "thin partitions" between greatness and psychopathology. Dr. Daniel Kevles, in his book In the Name of Eugenics, quotes Galton as saying that "men who leave their mark on the world are very often those who, being gifted and full of nervous power, are at the same time haunted and driven by a dominant idea, and are therefore within a measurable distance of insanity.")”
― Kay Redfield Jamison, Touched with Fire: Manic-Depressive Illness and the Artistic Temperament