Should you say it means that he has not fulfilled the precept of the white [threads] but has fulfilled the precept of the blue, but according to Rabbi the absence of one invalidates the other! — Rab Judah said in the name of Rab, It means that he has not fulfilled the precept and yet has performed the precept, for ‘has not fulfilled the precept’ only means that he has not performed the precept in the best way. This then explains the clause, NEITHER DOES THE WHITE INVALIDATE THE BLUE; but how can one explain the other clause, THE BLUE DOES NOT INVALIDATE THE WHITE? Moreover, it has been reported: Levi once said to Samuel, Arioch, you are not to sit down until you explain to me the following: THE BLUE DOES NOT INVALIDATE THE WHITE, NEITHER DOES THE WHITE INVALIDATE THE BLUE. What does it mean? — He answered, This refers to the fringes in a [white linen] garment; for it is proper to insert the white threads first, since Holy Writ says ‘the corner’, [signifying that the fringes] of the same [colour] as the corner [must be inserted first]; nevertheless, if one inserted the blue first it does not matter. Well, this explains. NEITHER DOES THE WHITE INVALIDATE THE BLUE, but how can one explain, THE BLUE DOES NOT INVALIDATE THE WHITE? — Rami b. Hama answered, The latter rule refers to a garment that is entirely blue, in which case it is proper to insert the blue threads first, since Holy Writ says ‘the corner’, [signifying that the fringes] of the same [colour] as the corner [must be inserted first]; nevertheless, if one inserted the white threads first it does not matter. Raba objected, Does then the colour affect the law? — Raba therefore explained that [our Mishnah] refers to the curtailment of the threads; thus whether the blue [threads] were curtailed and the white remained or the white were curtailed and the blue remained, it does not matter. As the sons of R. Hiyya said, Curtailed blue threads are valid; curtailed hyssop twigs are valid. What is the minimum length of a curtailed thread? — Bar Hamduri stated in the name of Samuel, There must be sufficient to make a loop therewith. The question was raised: Does ‘sufficient to make a loop’ mean to make a loop of all the threads together, or of each thread separately? — This remains undecided. R. Ashi raised the question: How is it if [the curtailed threads] are so thick that one cannot make a loop with them, although had they been thinner one could have made a loop with them? — R. Aha the son of Raba answered R. Ashi, They are most certainly [valid], since the precept is all the more noticeable thereby. Who is the Tanna that disagrees with Rabbi? — It is the Tanna of the following Baraitha. For it was taught: R. Isaac says in the name of R. Nathan who said it in the name of R. Jose the Galilean and who in turn said it in the name of R. Johanan b. Nuri, If a man has no blue threads he should insert all white threads. Raba said, You can infer from this that one must make a knot after each joint; for should you hold that this is not necessary, then how could the sons of R. Hiyya have said, Curtailed blue threads are valid, also curtailed hyssop twigs are valid? As soon as the upper knot becomes loose it would all become undone! —ᵃᵇᶜᵈᵉᶠᵍʰⁱʲᵏˡᵐⁿᵒ