I Corinthians xiv. 20–25 has long posed severalcruces interpretationisfor commentators. The basic problems concern the relationship of the assertions made about tongues and prophecy in υ. 22 to the quotation of Isa. xxviii. 11–12 in υ. 21 and to the illustrations concerning tongues and prophecy in υυ. 23–5. As to the quotation, J. Ruef remarks that most commentators admit to the difficulty of seeing how it substantiates Paul's conclusion that tongues are meant as a sign for the unbeliever. Concerning the illustrations, both J. Héring and J. P. M. Sweet note that in the light of the assertions we would expect them to be the reverse of what they are. While tongues are asserted to be meant as a sign for unbelievers and prophecy for believers, the illustrations depict the negative effect of tongues upon unbelievers and the positive effect of prophecy not on believers but upon unbelievers. The second assertion (υ. 22b) in particular contradicts the second illustration (υυ. 24–5) in that it clearly states that ‘prophecy is meant as a signnot for unbelieversbut for believers’. This is so if σημεĩον is taken in a positive sense. If, on the other hand, it is taken in a negative sense, the logical relation of this second illustration to the second assertion becomes ambiguous.