The same came to him by night, and said to him, "Rabbi, we know that you are a teacher come from God, for no one can do these signs that you do, unless God is with him."

 (ii) But there may be another reason. The rabbis declared that the best time to study the law was at night when a man was undisturbed. Throughout the day Jesus was surrounded by crowds of people all the time. It may well be that Nicodemus came to Jesus by night because he wanted an absolutely private and completely undisturbed time with Jesus. 