Sentence:  For they considered the odd numbers as male and the even ones as female , equating the two groups with the Yang and Yin principles in Nature ; and in this square , the respective pairs made up of large and small odd ( Yang ) numbers , and those composed of large and small even ( Yin ) numbers , <WSD>were</WSD> all equal to each other . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)