Why did Pythagoreans associate odd numbers with the male principle?

The Pythagoreans associated odd numbers with the male principle as part of their broader doctrine of opposites. In their philosophical system, odd numbers were identified with the "limit" or "limiting" force, which they viewed as an active, ordering principle that brings harmony to the "unlimited," represented by even numbers.1

This classification was formalized in the Pythagorean "table of ten opposites," which categorized various dualities—such as odd-even, right-left, and male-female—as fundamental components of the cosmos. Within this framework, odd numbers were symbolically linked to the male principle, while even numbers were associated with the female principle. This dualistic worldview suggested that these opposing forces "fit together" to create the order and structure of the universe.12