It’s not 100% known, but it is thought that King Solomon is the author of Ecclesiastes.
The words of the Preacher, the son of David, king in Jerusalem.
16 I said in my heart, “I have acquired great wisdom, surpassing all who were over Jerusalem before me, and my heart has had great experience of wisdom and knowledge.”Ecclesiastes 1:1, 16 (ESV)
You can also read this language in 1 Kings:
10 It pleased the Lord that Solomon had asked this. 11 And God said to him, “Because you have asked this, and have not asked for yourself long life or riches or the life of your enemies, but have asked for yourself understanding to discern what is right, 12 behold, I now do according to your word. Behold, I give you a wise and discerning mind, so that none like you has been before you and none like you shall arise after you. 13 I give you also what you have not asked, both riches and honor, so that no other king shall compare with you, all your days. 14 And if you will walk in my ways, keeping my statutes and my commandments, as your father David walked, then I will lengthen your days.”1 Kings 3:10-14 (ESV)
An interesting note: The name of the book, Ecclesiastes, refers to an assembly or gathering. The word in verse one translated as “Preacher” above could also be referred to as a Convener – one who gathers an assembly (or convention) together.
Lastly, there are going to be parts of Ecclesiastes that seem contradictory, but they aren’t necessarily so. The circumstances often determine whether you turn one way or the other, or whether you respond or not respond.
He has made everything beautiful in its time. Also, he has put eternity into man’s heart, yet so that he cannot find out what God has done from the beginning to the end.Ecclesiastes 1:11 (ESV)
A phrase from my Bible study this morning that really struck me:
If we could understand God, then He’s not big enough.
We’re not supposed to understand the mysteries of God, despite being given minds that are hard wired to try and figure things out. That’s where faith comes in.