In Isaiah 49:10, this signifies knowledge of truth from the Word. (Arcana Coelestia 8568[7])

In Genesis 49:22, this signifies the abundance of truth from the Word. (Arcana Coelestia 6418)

In Isaiah 41:18, this signifies to fill the natural with truths. (Apocalypse Explained 304[21])

In Hosea 13:15, this signifies doctrine destroyed, and fountain signifies the Word. (Apocalypse Explained 730[12])

A fountain, as in Psalm 104:10, denotes knowledges.

(References: Apocalypse Revealed 360, 384; Revelation 7, 16, 16:7)