Eccl. 3:11 (NIV)
He has made everything beautiful in its time. He has also set eternity in the hearts of men; yet they cannot fathom what God has done from beginning to end.
The paraphrase of how it could be translated:
God has made everything appropriate in its time. He has placed darkness in the human heart so that people cannot discover all God has done.
I encourage you to read the article, because this isn't just about a word translation. It speaks to our desire for an explanation for evil. Why do bad things happen? Why must there be a time to be born and a time to die? A time to weep and a time to laugh? A time for war and a time for peace?
The response is that this is simply what God has chosen to do and it isn't for us to question Him. Just trust God.