H. P. Blavatsky wrote:
Imagination is, again, one of the strongest elements in human nature, or in the words of Dugald Stewart it “is the great spring of human activity, and the principal source of human improvement.
. . . . Destroy the faculty, and the condition of men will become as stationary as that of brutes.” It is the best guide of our blind senses, without which the latter could never lead us beyond matter and its illusions. The greatest discoveries of modern science are due to the imaginative faculty of the discoverers.
- Helena Petrovna Blavatsky, Collected Writings vol. XII (Wheaton, IL: Theosophical Publishing House, 1980), 133-134.