as for those among the people of the world who claim that semen has the power to form a fetus either from it or from menstrual blood they have proven the validity of that by saying that if semen is not in the womb there is no fetus. it is said to them if the fetus were to be formed by semen it could be in the womb and the months would be completed for it and the woman would not find any defect and there would be no fetus. we do not see the existence of semen except as being in the same position as its nonexistence. it is said to them how do you know that perhaps the fetus is formed in the womb by semen? these are conjectures of evidence.
وأما من زعم من أهل الدهر أن في المني قوة تصور الجنين إما منه وإما من دم الطمث فإنهم استدلوا على صحة ذلك بأن المني إذا لم يكن في الرحم لم يكن جنين، فيقال لهم ولو كان بكون المني يكون الجنين فقد يكون في الرحم وتتم له الشهور ولا تجد المرأة علة ولا يكون الجنين، فلسنا نرى وجود المني إلا بمنزلة عدمه. ويقال لهم ما يدريكم لعل في الرحم تصور الجنين في المني؟ وهذه ظنون الاستدلالات