I Corinthians 8:1 says, "Knowledge puffs up, but love edifies [builds up]." "Puffs up," when opposed to "edifies," implies tearing down, destruction. Paul is saying that pride has the power to corrupt the bearer of knowledge. This statement is part of the prologue to the great chapter on love, written because the Corinthians had allowed their emphasis to drift into the wrong areas. Even as a gift from God, knowledge has the potential to corrupt its recipient, if it is unaccompanied by love.
Paul thus begins chapter 13 by contrasting love with other gifts of God. He does this to emphasize love's importance, completeness, permanence, and supremacy over all other qualities we consider important to life and/or God's purpose.
Prophecies end because they are fulfilled. The gift of tongues is less necessary today as then because of the widespread use of English in commerce, politics and academia. Its value depends on specific needs. Knowledge is increasing so rapidly that old knowledge, especially in technical areas, becomes obsolete as new developments arise. Yet the need for love is never exhausted; it never becomes obsolete. God wants us to use it on every occasion.