God has given the children of men to travail in travail (v. 10).
God has made everything beautiful in its own time and has put eternity (an aspiration for the things in eternity) in man's heart, yet so that man does not find out what God has done from the beginning to the end (v. 11). In His creation of man, God put something into man which Solomon called "eternity." This means that in man there is a kind of aspiration for God, an aspiration for something eternal. Physical things may be enjoyable, but they are temporal.
Many successful people can testify that when they were endeavoring to advance in their career, they sensed that there was an emptiness within them. They began to realize that they were seeking something eternal. After they gained something they wanted, they felt that it was nothing. This feeling comes from the aspiration in man's heart for something eternal.
According to our own experience we know that whenever we have a success in our human life, we also have an empty feeling. This indicates that within man there is an aspiration for eternal things. God has put such an aspiration, such a seeking, in man's heart so that he will seek God. Every person, especially every thoughtful person, has within him this longing and seeking for eternity.
Verses 12 and 13 say that there is nothing better for man than to rejoice and do good in his lifetime, eating, drinking, and tasting enjoyment in all his labor; it is the gift of God.
God created man for Himself, but man was seduced by Satan to give God up, and thus man became fallen. Nevertheless, God still blesses man so that he may have a good living and enjoy various material things. By blessing man with material things, God maintains the existence of mankind from generation to generation. God has preserved man in this way for the sake of the redemption of His chosen ones.
Apart from God's blessing no one could bear to live on earth. On the one hand, everything under the sun is vanity of vanities and is subject to the slavery of corruption. On the other hand, certain things in human life, such as education, work, and marriage, are still very appealing. If we did not strive to gain an education or to succeed in our work or to have a good married life and family life, we might be tempted to commit suicide. God uses man's striving for these things in order to keep man on earth. If mankind ceased to exist, God could not gain His chosen ones from among the fallen human race. If mankind had been terminated, Christ could not have come, for there would have been no lineage for His incarnation.
Although man is fallen, God continues to bless man, causing the sun to shine and the rain to fall and maintaining a proper order in the universe. As a result, people have the desire to go on living. In this way mankind is preserved for God to fulfill His purpose in choosing us before the foundation of the earth.
We were born at the right time and in the right place. Therefore, we all are here today for God's purpose. Without God's sovereign preservation of physical, human life, none of us could exist for His purpose. I believe that this is the correct understanding of Solomon's thought when he wrote that "every man should eat and drink and taste enjoyment in all his labor; it is the gift of God" (v. 13).