For the first time in 50 years of computer science, a metaphor of programming has been proposed that most people can relate to—objects have true identity, and objects are conserved. As in the real world, an object cannot be copied or destroyed without first filling out a lot of forms, but on the other hand, the transmission of objects is relatively painless. An object is localized in space, and can move from place to place. (Only computer-literate people must be told that the transmission of these objects does not create copies.) Linear logic finally makes precise the high school notion that a function is like a box into which one puts argument values and receives result values, and that a truly “functional” box does not remember its previous arguments or results. — Henry G. Baker, “Linear Logic and Permutation Stacks—The Forth Shall Be First”