Niddah

'If another three 'onahs have passed over her and then again she observed a discharge it suffices for her to reckon her uncleanness from the time she observed it'. What is the ruling where she again observes discharges at the end of single 'onahs?  — R. Kahana citing R. Giddal who had it from Rab replied: After the first time it suffices for her to reckon her uncleanness from the time she observed the discharge but after the second time she causes uncleanness retrospectively for twenty-four hours or from her previous examination to her last examination. Whose view does this  represent? That of Rabbi who laid down that if a thing has occurred twice presumption is established.  Read then the final clause:  'If subsequently three 'onahs have passed over her and then she again observed a discharge, it suffices for her to reckon her uncleanness from the time she observed it'. Does not this agree only with the view of R. Eliezer?  And should you reply that it in fact represents the view of Rabbi but that in the case of [an interval of three] 'onahs he holds the same view as R. Eliezer, [it could be retorted]: Does he indeed hold the same view seeing that it was stated, 'After he reminded himself'?  — The fact is that it represents the view of R. Eliezer but  [in respect of presumption in the case of] menstrual periods he is of the same opinion as Rabbi. A stain [discovered by one who had not yet reached the age of menstruation] between her first and second [observation of a discharge] is regarded as clean,  but as regards one discovered between her second and third observation, Hezekiah ruled: It is unclean, while R. Johanan ruled: It is clean. 'Hezekiah ruled: It is unclean', since, when she observed [a discharge for the third time] she becomes unclean [retrospectively],  her stain also  causes her to be unclean; 'while R. Johanan ruled: It is clean,' for this reason: Since  she was not yet confirmed in the condition of presumptive menstruation  she cannot be regarded as unclean on account of her stain.