Biscuit (bread) cooking, most often based on ground wheat and warmed with gravy. The biscuit emerged as a distinct food type in the early 19th century, before the American Civil War. Cooks created a cheaply produced addition for their meals that required no yeast, which was expensive and difficult to store. With no leavening agents except the bitter-tasting pearlash available, beaten biscuits were laboriously beaten and folded to incorporate air into the dough which expanded when heated in the oven causing the biscuit to rise. In eating, the advantage of the biscuit over a slice of bread was that it was harder,
Mental substance Mental substance Mental substance is the idea held by dualists and idealists, that minds are made-up of non-physical substance. This substance is often referred to as consciousness. This is opposed to the materialists, who hold that what we normally think of as mental substance is ultimately physical matter (i.e., brains). Descartes, who was most famous for the assertion "I think therefore I am", has had a lot of influence on the mind–body problem. He describes his theory of mental substance (which he calls res cogitans distinguishing it from the "res extensa") in the "Second Meditation" (II.8) and in "Principia Philosophiae"