1 Corinthians 4:17

For this cause have I sent unto you Timotheus, who is my beloved son, and faithful in the Lord, who shall bring you into remembrance of my ways which be in Christ, as I teach every where in every church (KJV)

Then: Obviously, Paul has finished explaining that he wants the Corinthians to think and therefore act as followers of Christ. Those who follow him follow Christ. Now he is sending Timothy, one who knows Paul, and more importantly, knows Christ. N. T. Wright (p. 52-53) brings in the aspect of authority. Paul cannot leave it to the Corinthians to vote and say, "Paul is right. We're off track in our understandings and attitudes towards each other. It's time to change." Neither can he come in, dictate saying "Behave. Reflect, change, and be like Christ." Christ's authority and power in the church does not match any of the world's organizational structures. For actually, Paul's authority affects believers through the Holy Spirit and through prayer. Paul just needs to be sure the Corinthians hear the gospel again. It is the power of Christ which effects changed hearts, minds, and actions. To that end, Paul now sends Timothy.

Now: Matthew Henry notes that people being people just forget; reteaching has its own power of conviction. The same gospel comes to all the apostles to every church and every person. It does not change, but the hearers do. When Paul sends Timothy, the message is again coming whether directly through Paul is not important.

Extra Sources: Commentary on the Whole Bible Acts to Revelation Vol VI by Matthew Henry online at http://www.ccel.org/ccel/henry/mhc6.iCor.v.html