Here God uses figurative language to say he will reverse the bad situation of the people of Israel, which they complained about in 40.27. He primarily compares them to blind people. He will guide them and even let them see light, which means their blindness is gone. Good News Translation makes it clear that he is speaking about his own people by saying “my blind people.”
The first four lines of this verse have a chiastic structure, which is visible in Revised Standard Version.
And I will lead the blind in a way that they know not: Here God says he will personally lead those who are blind on roads they have not traveled before. The blind is an image for God’s people. Sometimes this image is used in Isaiah to indicate that they are disobedient and stubborn (see 43.8; 56.10; see also the comments on Isa 42.7 and 29.18), but here it refers to their exile in Babylonia. We recommend that translators render it literally to keep the imagery. A way that they know not may be rendered “unfamiliar paths.”
In paths that they have not known I will guide them is parallel and synonymous with the previous two lines. I will guide them is literally “I will cause them to walk.” It may be rendered “I will make them walk safely.” Good News Translation combines these two lines into the previous two, saying “I will lead my blind people by roads they have never traveled.”
I will turn the darkness before them into light means God will enable the blind to see (compare verse 7a). The darkness here is an image for the hopeless situation of his people, while the light represents their bright new future. God will bring them out of exile. There may be a connection here to the Exodus tradition, which speaks about the light God provided for his people (see, for example, Exo 13.21).
The rough places into level ground is parallel with the previous line. The verb phrase I will turn is implied here. This line is another image for the return of God’s people from exile. The rough places refer to their present bad situation, while the level ground points to a better future. Most versions use here the imagery of making rough roads level, so that they are easy to travel (compare 40.3-4). However, since the Hebrew noun rendered rough places refers to something twisted or crooked, some versions use the imagery of making crooked roads straight; for example, Revised English Bible says “and make straight their twisting roads” (similarly New American Bible). Translators may choose either interpretation.
These are the things I will do, and I will not forsake them. In these two parallel lines God emphasizes that he will fulfill what he has just promised to do for his people. The Hebrew verbs rendered will do and will … forsake are in the perfect form, which indicates certainty. It is as though these actions have been completed already. I will not forsake them repeats God’s promise in 41.17. The pronoun them refers back to the blind, who are the people of Israel.
For the translation of this verse consider the following examples:
• I will lead those who are blind
on roads they have never traveled before,
on paths they have never gone before
I will lead them.
Their darkness I will turn to light,
and their rough ground I will make smooth.
This is what I will do for them,
never forsaking them.
• I will guide the blind along unfamiliar ways,
on paths they have never walked before I will lead them.
I will turn their darkness into light,
and I will make their rough ground smooth.
This is what I will do,
and I will never abandon them.
Quoted with permission from Ogden, Graham S. and Sterk, Jan. A Handbook on Isaiah. (UBS Helps for Translators). New York: UBS, 2011. For this and other handbooks for translators see here .