This. book. is. a. compact. introduction. to. many. of. the. important. topics. of. mathematical. logic,. comprising. natural. and. unrestricted. set-theoretic. methods..Here.is.a.very.brief.sketch.of.some.of.its.contents:. 1..One. of. the. most. prominent. features. of. this. new. edition. is. a. consistency. proof. for. formal. number.theory.due.to.Kurt.Schütte..This. proof.had.been.included.in.the.first.edition.in.1964..It.was.dropped. in. later. editions. and. is. now. brought. back. by. “popular. demand.”. Quite.a.few.people.thought.I.had.made.a.mistake.in.abandoning.it... 2..There.is.now.a.greatly.enlarged.bibliography,.with.items.that.should. be. interesting. to. a. wide. audience.. Many. of. them. have. to. do. with. the.philosophical.significance.of.some.important.results.of.modern. mathematical.logic. As. before,. the. material. in. this. book. can. be. covered. in. two. semesters,. but. Chapters. 1. through. 3. are. quite. adequate. for. a. one-semester. course.. Bibliographic.references.are.aimed.at.giving.the.best.source.of.information,. which. is.not. always. the.earliest;. hence,. these. references. give.no. indication.of.priority