Charles Ellicott Commentary Psalms 84:5

"Blessed is the man whose strength is in thee; In whose heart are the highways [to Zion]." — Psalms 84:5 (ASV)

Blessed is the man. —Or collectively, men, as the suffix in their hearts shows.

Ways. —The word derives from a root meaning to cast up, and so refers to highways marked by the heaps of stone piled up at the side (Isaiah 57:14). In Jeremiah 18:15, mere footways or bypaths are contrasted with these. Consequently, the highway lends itself as a metaphor for the way of peace and righteousness (Proverbs 12:28), an interpretation adopted by the Chaldee and some modern expositors.

However, this moral intention is secondary to the actual desire to join the pilgrim band journeying towards Zion; the verse describes this in words that are echoed exactly in our own Chaucer:

“So pricketh hem Nature in her corages (in their hearts)
Than longen folk to go on pilgrimages.”

The well-known and deeply loved route to the sacred shrine is in their minds; their hearts are set upon it.