 This entry is intended to assist the student of PM in reading the symbolic portion of the work. What follows is a partial translation of the symbolism into a more contemporary notation, which should be familiar from other articles in this Encyclopedia, and which is quite standard in contemporary textbooks of symbolic logic. No complete algorithm is supplied, rather various suggestions are intended to help the reader learn the symbolism of PM. Many issues of interpretation would be prejudged by only using contemporary notation, and many details that are unique to PM depend on that notation. It will be seen below, with some of the more contentious aspects of the notation, that doctrines of substance are built into the notation of PM. Replacing the notation with a more modern symbolism would drastically alter the very content of the book.