Evidently the people of Jesus’ day believed that it was necessary for a person to “have light in himself” in order for him to see. Accordingly the two parts of this verse supplement each other. A person stumbles at night not only because of the lack of external light, but also because he has no light.

He has no light can be misleading, since it may suggest that “he has no torch.” It is important to understand the passage as referring to an internal source of light or capacity to see in the darkness.

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .