Ecclesiastes.

Ecclesiastes
HERE we have the experience of a wise man—endued with wisdom by God, having almost everything on earth that his heart desired, and finding “all vanity and vexation of spirit.” He looks too at others in their various circumstances, and notices many sore evils. Even as to knowledge, he found “in much wisdom is much grief, and he that inereaseth knowledge increaeeth sorrow.” It is an important book, because it answers the question which almost everyone is trying to solve, “Is there an object on the earth that can satisfy the heart of man?” The reply is, No— “all is vanity and vexation of spirit.”
It hints, however, at the fact that God is the alone spring of joy. “Go thy way, eat thy bread with joy, and drink thy wine with a merry heart; for God now aecepteth thy works.” (chapter 9:7.)
There are also two exceptions made to all being vanity under the sun. One is a figurative or parabolic allusion to the finished work of Jesus, who by His death delivered us from the wrath to come. “This wisdom have I seen also under the sun, and it seemed great unto me. There was a little city, and few men within it; and there came a great king against it, and besieged it, and built great bulwarks against it; now there was found in it a poor, wise man, and he, by his wisdom, delivered the city.” Surely the death of Christ was enacted under the sun, and great indeed was that work. He was emphatically the poor, wise man, and He delivered us from death, and him that had the power of death. This surely is not vanity—all is substantial and everlasting in its value and results. Yet how true it is that “no man remembered that same poor man.” (chapters 9:13, 15.)
The present service of the Lord is another exception. Surely it is not vanity, and instead of being connected with vexation of spirit, we all know that “His yoke is easy, and His burden is light.” Hence we read, “Cast thy bread upon the waters, and thou shalt find it after many days.” (chapter 11:1.)
The great lesson drawn from the book is to fear God, and be obedient to His word. (chapter 12:13.)