In Matthew 3:13, we have the verb, βαπτιζω (4/77), used again.  This time something different happens.  

Who is coming to be baptized? Jesus of all people is coming to be baptized by John
Where is the Baptism happening? Well Jesus traveled from Galilee and came to John by the Jordan to be baptized.  
Why is Jesus coming to be baptized by John? We know that John's baptism is for repentance, it is for those who are trying to flee the wrath of God, but Jesus is the Son of God. He has no sin, He doesn't need to repent, and He isn't going to flee the wrath of God, He is going to confront it on Golgotha!  

Thankfully in the next verse we have another use of Baptism. Because this verse bucks the trend of the previous verses. Jesus has no sin, and if He has no sin, then He has no need of repentance.  So what is going on here? Thankfully v14 also has the same verb and so we can look for some more answers.

In Matthew 3:14, we have the same verb, βαπτιζω (5/77).  John is just as confused as we ought to be. Why is the Son of God getting baptized?  John protests and says that he, John, needs to be baptized by Jesus.  

Who is baptizing who right now?  Well John is baptzing Jesus.
Why does Jesus need to get Baptized?  The reason that Jesus gives John is He needs to be Baptized to fulfill all righteousness.  

Now that word righteousness in the Greek is δικαιοσύνη, which is to be declared innocent.  Now if Baptism is something that we do, and Baptism fulfills, or completes our righteousness, innocence, before God.  Then Jesus is saying here that the works we do save us.  If the Baptism of John is from Man, then man is saved by His works.  However, if Baptism is from heaven, and is instead the work of God, then we are saved by God's work.  

So is Baptism from God or from Man?