John Calvin Commentary Isaiah 58:11

"and Jehovah will guide thee continually, and satisfy thy soul in dry places, and make strong thy bones; and thou shalt be like a watered garden, and like a spring of water, whose waters fail not." — Isaiah 58:11 (ASV)

And Jehovah will always conduct you. He now describes more clearly what he had spoken briefly and figuratively, that God will be their guide, so that they will lack nothing for a full abundance of blessings. God is said to “conduct” us when we actually feel that he goes before us, as if he were placed before our eyes.

And will satisfy your soul in drought. The Prophet adds that the aid promised will not be of short duration, because God never forsakes his people in the middle of the journey but continues his kindness toward them with unwearied regularity. For this reason, he promises that they will be satisfied amid the deepest poverty, because God never lacks any benefits for relieving their poverty, and his act of blessing is of more value than the most abundant rains of the whole year.

And yet he does not promise believers a rich and abundant produce of fruits or a plentiful harvest, but that God will nourish them, though the earth yields no food. In this way, he instructs them to depend on God’s assistance and be satisfied with it, though they are not altogether free from the distresses of famine. In this sense he adds:

And will make fat your bones. He does not say that they will be fully and highly fattened, but that they will be so lean that the “bones” will protrude even through the skin. Thus, he gives the appellation of “bones” to those who have been worn bare by hunger or famine—men who have hardly anything remaining but dry skin and “bones.” And he means that the Jews will have to contend with a lack of all things and with leanness, until God restores them.

Of the same import are the metaphors which he adds: a watered garden, and a spring of waters. Isaiah cannot satisfy himself in describing the kindness of God, which he displays toward his sincere worshippers, so that people may not seek anywhere else than in themselves the causes of barrenness. It amounts to this: that this fountain of God’s kindness never dries up but always flows, if we do not stop its course by our own fault.