Desire to know why, and how, Curiosity; such as is in no living creature but Man: so that man is distinguished, not only by his Reason, but also by this singular Passion from other Animals; in whom the appetite of food, and other pleasures of Sense, by predominance, take away the care of knowing causes; which is a Lust of the mind, that by a perseverance of delight in the continual and indefatigable generation of Knowledge, exceedeth the short vehemence of any carnal pleasure.

Thomas Hobbes, in Leviathan, part I, chapter 6