Cast your bread upon the waters, for you will find it after many days. Give a portion to seven, or even to eight, for you know not what disaster may happen on earth. If the clouds are full of rain, they empty themselves on the earth, and if a tree falls to the south or to the north, in the place where the tree falls, there it will lie. He who observes the wind will not sow, and he who regards the clouds will not reap.

As you do not know the way the spirit comes to the bones in the womb of a woman with child, so you do not know the work of God who makes everything. In the morning sow your seed, and at evening withhold not your hand, for you do not know which will prosper, this or that, or whether both alike will be good. Ecclesiastes 11:1-6 (ESV)