This has been taught only with reference to defilement, but with regard to eating, clean animals form one group for themselves and unclean animals another. And Levi said: Also in regard to eating do they all combine with one another. And R. Assi said: Clean animals for themselves and unclean for themselves. Some say he differs from Rab, while others say he does not differ from him. An objection was raised: [The flesh of] a dead cow and a living camel cannot combine with one another, from which it follows that if both, however, were dead their flesh would combine. Does this not contradict R. Assi? — No, refer thus: But if both were alive they could combine; and this would be in agreement with R. Judah's view who holds that the prohibition to eat a limb [cut off] from a living creature applies also to unclean animals. But what would be the case if both were dead? Could they not combine? If so, why just instance ‘the flesh of a dead cow and a living camel’, surely even if both were dead they could not combine? And furthermore, have we not learnt: ‘Half an olive size [of the flesh] of a living cow and half an olive-size of that of a dead camel cannot combine with one another, but half an olive size of the flesh of a cow and half an olive-size of that of a camel can combine with one another if both are alive or both dead’. There would be a contradiction between the opening clause and the concluding. You must therefore come to the conclusion that in the case of both animals being dead they can combine with one another! — R. Assi would reply: This Tanna holds that a prohibition can apply to something that has been prohibited already by reason of another prohibition. 17ᵃᵇᶜᵈᵉᶠᵍʰⁱʲᵏˡᵐⁿᵒᵖᵠ