Solomon is the writer. This fact is very well established among conservative expositors, and there is no other reasonable explanation for the book.
Solomon also wrote the Books of Proverbs and the Song of Solomon. We will find Ecclesiastes to be quite different from the Book of Proverbs. In Proverbs we saw the wisdom of Solomon; here we shall see the foolishness of Solomon. Ecclesiastes is the dramatic autobiography of his life when he was away from God.
Ecclesiastes indicates a preacher or a philosopher. I rather like the term philosopher because it is less likely to be misunderstood.
To correctly understand any book of the Bible, it is important to know the purpose for which it was written. We need to back off and get a perspective of the book. We need to put down the telescope on the Word of God before we pick up the microscope. The necessity for this is more evident here than in many of the other books of the Bible.
This is human philosophy apart from God, which must always reach the conclusions that this book reaches. We need to understand this about Ecclesiastes because there are many statements which contradict certain other statements of Scripture.
Actually, it almost frightens us to know that this book has been the favorite of atheists, and they have quoted from it profusely. Voltaire is an example. Today we find the cynic and the critic are apt to quote from this book. And it is quite interesting to note the number of cults that use passages from this book out of context and give them an entirely wrong meaning.
Man has tried to be happy without God; it is being tried every day by millions of people. This book shows the absurdity of the attempt. Solomon was the wisest of men, and he had a wisdom that was God–given. He tried every field of endeavor and pleasure that was known to man, and his conclusion was that all is vanity. The word vanity means “empty, purposeless.” Satisfaction in life can never be attained in this manner.
God showed Job, a righteous man, that he was a sinner in God’s sight. In Ecclesiastes God showed Solomon, the wisest man, that he was a fool in God’s sight. This is a book from which a great many professors, Ph.D.s and Th.D.s, and preachers could learn a great lesson. In spite of all their wisdom, in spite of all attempts at being intellectual, unregenerate men in the sight of God are fools. That, my friend, is something that is hard to swallow for those who put an emphasis upon their I.Q. and the amount of knowledge and information that they have accumulated.
In Ecclesiastes we learn that without Christ we cannot be satisfied—even if we possess the whole world and all the things that men consider necessary to make their hearts content. The world cannot satisfy the heart because the heart is too large for the object. In the Song of Solomon, we will learn that if we turn from the world and set our affections on Christ, we cannot fathom the infinite preciousness of His love; the Object is too large for the heart.
The key word is vanity, which occurs thirty–seven times. The key phrase is “under the sun,” which occurs twenty–nine times. Another phrase which recurs is “I said in mine heart.” In other words, this book contains the cogitations of man’s heart. These are conclusions which men have reached through their own intelligence, their own experiments. Although Solomon’s conclusions are not inspired, the Scripture that tells us about them is inspired. This is the reason for the explanatory: “I said in mine heart,” “under the sun,” and “vanity.”
(McGee, J. Vernon. Thru the Bible Commentary, Vol. 21: Ecclesiastes & Song of Solomon. Nashville, TN: Thomas Nelson Publishers, 1991.)