## A quotation by Reinhold Baer

The main result of Gödel's paper ... can be formulated in a pointed and, hence not fully correct way as follows: if

*A*is a countable, consistent logical system, for example arithmetic, then there is a proposition in

*A*which is not decidable in

*A*(but may be decidable in extended systems). Hurrah, logicians have also discovered diagonalisation!

Letter to Zermelo in 1931