Passage
Day vnto day vttereth the same, and night vnto night teacheth knowledge.
Day vnto day vttereth the same, and night vnto night teacheth knowledge.
Psalms 19:1 To him that excelleth. A Psalme of Dauid. The heauens declare the glory of God, and the firmament sheweth ye worke of his hands.
Psalms 19:2 Day vnto day vttereth the same, and night vnto night teacheth knowledge.
Psalms 19:3 There is no speach nor language, where their voyce is not heard.
Psalms 19:4 Their line is gone forth through all the earth, and their words into the endes of the world: in them hath he set a tabernacle for the sunne.
The verse centers on "vnto", "vttereth", "same", "night", "teacheth", and "knowledge". It is saying that the verse draws attention to "vnto" and "vttereth", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 1's "To him that excelleth A Psalme of..." into verse 3's "There is no speach nor language where...", so "vnto" and "vttereth" belong inside that flow. In Psalms context, the local focus is worship, trust, the LORD's kingship, and covenant mercy.
A plain takeaway is to answer the verse's own emphasis on "vnto" and "vttereth" with trust shaped by these words, not by a vague optimism outside the passage.