What Is Numerology? This is a short booklet which gives an in depth definition of numerology together with a discussion of the basic ways that it is used. This booklet does not teach how to do numerology. Numerology was famously practiced by Pythagoras and his school of philosophers and mathematicians in what is now Crotone in the heel of the boot of Italy. Numerology postulates that the forces of the natural world can be read and interpreted by the use of the numbers which define these forces.