[3:2] sn Possibly Nicodemus came…at night because he was afraid of public association with Jesus, or he wanted a lengthy discussion without interruptions; no explanation for the timing of the interview is given by the author. But the timing is significant for John in terms of the light-darkness motif – compare John 9:4, 11:10, 13:30 (especially), 19:39, and 21:3. Out of the darkness of his life and religiosity Nicodemus came to the Light of the world. The author probably had multiple meanings or associations in mind here, as is often the case.
[3:2] 3 sn The reference to signs (σημεῖα, shmeia) forms a link with John 2:23-25. Those people in Jerusalem believed in Jesus because of the signs he had performed. Nicodemus had apparently seen them too. But for Nicodemus all the signs meant is that Jesus was a great teacher sent from God. His approach to Jesus was well-intentioned but theologically inadequate; he had failed to grasp the messianic implications of the miraculous signs.