The Lord uses objects which we know to illustrate great unseen things which we do not know; and the harp is so used.
WHO IS GOD?
[6]Before we can know God and understand his great plan it is first necessary for us to believe that he exists and that he rewards all who diligently seek him.

(Hebrews 11:6) But how can we believe?
We must first have some knowledge.

But how can we know that there is a great God?
Let us look at some of the simpler things about us and reason upon the matter.
[7]Look at the flowers in your garden.

Out from the same soil grow the many varieties of different hues and colors.

Likewise from the same soil spring the divers kinds of trees, bringing forth different fruits at different seasons of the year.