Luke 3:5

Every valley, &c. If these words, in one sense, were a prediction of the deliverance of the Israelites from their captivity, (Isaias xl. 3.) and an admonition to level the roads for those that were to return, they also signified the redemption of mankind from the slavery of sin; and that all obstacles, which retard this benefit, should be removed, and also that the proud should be depressed, and the humble receive graces. (Witham)