4 We have said who the brethren were, let us hear what they said: “Pass over hence, and go into Judea, that your disciples also may see your work which you do.” The Lord's works were not hid from the disciples, but to these men they were not apparent. They might have Christ for a kinsman, but through that very relationship they disdained to believe in Him. It is told us in the Gospel; for we dare not hold this as a mere opinion, you have just now heard it. They go on advising Him: “For no man does anything in secret, and he himself seeks to be known openly: if you do these things, show yourself to the world.” And directly after it says: “For neither did His brethren believe in Him.” Why did they not believe in Him? Because they sought human glory. For as to what His brethren appear to advise Him, they consult for His glory. You do marvellous works, make yourself known; that is, appear to all, that you may be praised by all. The flesh spoke to the flesh; but the flesh without God, to the flesh with God. It was the wisdom of the flesh speak ing to the Word which became flesh and dwelt among us.
Source: Tractates on the Gospel of John (New Advent)