1900, 28-year-old Russell went to Paris to attend an international conference of philosophers and met an Italian logician named piano. The logician put forward a symbolic system, which inspired him to think that the laws of logic should be expressed by symbols, and mathematics is actually a branch of logic. In other words, all pure mathematics only studies the concepts defined by a few basic logic concepts, and all pure mathematics can be derived from a few basic logic principles. In his book "Fundamentals of Mathematics" published this year, he preliminarily expounded the view that mathematics and logic are the same. After returning to Cambridge University, Russell discussed this view with his teacher and famous mathematician Whitehead. Whitehead appreciated his point of view. Since then, the two have worked together to study mathematical logic.