There is the sense that he is on a journey. It is a prayer to be led from darkness to light. The words take on double meanings, from the situation in which he is when writing, and from the wider view of the church and the world by which he is so troubled. He confesses that he has liked to think of himself as being in control of his life and now knows that he is not. He needs guidance. The last two lines are for the reader and singer to interpret as they prove most helpful. Newman himself, when asked about them, refused to tie himself down to one meaning.
The composer was a music teacher and church organist in London. He was a pioneer in programme notes for concerts (and thus, presumably, the father of such notes as these!). The words were not written to be sung and are in a complex metre with the sense running over from line to line. This tune, which was written for the words, deals with them by being very simple, and expecting that the hymn should be sung intelligently.
from notes by Alan Luff © 2004