“What is Imagination? We talk much of Imagination. We talk of Imagination of Poets, the Imagination of Artists; I am inclined to think that in general we don’t know very exactly what we are talking about. Imagination I think especially two fold.

“First: it is the Combining Faculty. It brings together things, facts, ideas, conceptions, in new, original, endless, ever varying, Combinations. It seizes points in common, between subjects having no very apparent connexion, & hence seldom or never brought into juxtaposition.

“Secondly: It conceives & brings into mental presences that which is far away, or invisible, or which in short does not exist within our physical & conscious cognizance. Hence is it especially the religious faculty; the ground-work of Faith. It is a God-like, a noble faculty. It renders earth tolerable (at least should do so); it teaches us to live, in the tone of the eternal.

“Imagination is the Discovering Faculty, pre-eminently. It is that which penetrates into the unseen worlds around us, the worlds of Science. It is that which feels & discovers what is, the real which we see not, which exists not for our senses. Those who have learned to walk on the threshold of the unknown worlds, by means of what are commonly termed par excellence the exact sciences, may then with the fair white wings of Imagination hope to soar further into the unexplored amidst which we live.”

by Ada Lovelace, 1815-1852 (co-inventor of the computer with Charles Babbage)