Calculus Gems, a collection of essays written about mathematicians and mathematics, is a spin-off of two appendices (Biographical Notes and Variety of Additional Topics) found in Simmons' 1985 calculus book. With many additions and some minor adjustments, the material will now be available in a separate softcover volume. The text is suitable as a supplement for a calculus course and/or a history of mathematics course, The overall aim is bound up in the question, What is mathematics for? and in Simmons' answer, To delight the mind and help us understand the world. The essays are independent of one another, allowing the instructor to pick and choose among them.