Maybe not an inspirational quote, but every now and then you run across something someone has said (or written) that is so bang on that you just have to remember it :
“Sorrow is knowledge, they who know the most must mourn the deepest o'er the fatal truth, the Tree of Knowledge is not that of Life.”
(Lord Byron, Manfred, Act I, Scene I)
He clearly understood Solomon's lament and was a dim modern-day parallel :
I communed with mine own heart, saying, Lo, I am come to great estate, and have gotten more wisdom than all they that have been before me in Jerusalem: yea, my heart had great experience of wisdom and knowledge.
And I gave my heart to know wisdom, and to know madness and folly: I perceived that this also is vexation of spirit.
For in much wisdom is much grief: and he that increaseth knowledge increaseth sorrow.
Ecclesiastes 1:16-18
That gift of wisdom that Solomon had was a source of sorrow - lacking the true Knowledge of God.