Sentence:  Some poems, echoing the purpose of early poetic treatises on scientific principles, attempt to elucidate the mathematical concepts that underlie <WSD>prime numbers</WSD>. Others play with primes' cultural associations. Still others derive their structure from mathematical patterns involving primes. 
Meaning of the word marked with <WSD> tags:  Any natural number greater than 1 that is divisible only by itself and 1.