John Calvin Commentary Psalms 84:7

"They go from strength to strength; Every one of them appeareth before God in Zion." — Psalms 84:7 (ASV)

They will go from strength to strength. In this verse, the same sentiment is repeated. Mount Zion being the place where, according to the appointment of the law, the holy assemblies were observed after the ark of the covenant was removed there, it is said that the people of God will come to Zion in great numbers, provoking one another to this good work.

The word חיל, chayil, seldom signifies a troop, or band of men, but most commonly power, or strength. It will therefore be more in accordance with the ordinary use of the term, to translate, They will go from strength to strength; implying that the saints are continually acquiring fresh strength for going up to Mount Zion and continue to pursue their journey without weariness or fatigue, until they reach the wished-for place and behold the countenance of God. If the word troop is preferred, the meaning will be that not a few only will come, but numerous companies. The manner in which God manifested himself to his servants in the temple in ancient times, we have spoken of elsewhere, and especially on Psalm 27:4-5. No visible image of God was there to be seen; but the ark of the covenant was a symbol of his presence, and genuine worshippers found from experience that by this means they were greatly aided in approaching him.