Officially, 18.090 (often cross-listed with 18.901A in older catalogs) introduces students to the language and logic of mathematics. It covers:

, staring at the white space on his paper. He tried to list them. 2, 3, 5, 7... but they never ended. How do you talk about 'never ending' without getting lost in the void? Then, he remembered a line from the course description