To Florus 2.61

Yet if the apostle had meant anything of the kind here, he would have said sin entered ‘through one flesh,’ not ‘through one man.’ In generation, only the substance of flesh is shared with the offspring: a soul is not derived from a soul, but flesh from flesh. The term ‘human being,’ however, properly includes both mind and body. Thus, by naming one human being, the apostle neither indicated the work of fertility—in which he knew nothing was imparted except the substance of flesh—nor intended two to be understood. He stressed one to teach that sin passed by imitation, not generation (compare Romans 5:12).