Answer:
I am round as a bowl, deep as a tub, but all the world's water couldn't fill me up.
I am nothing but holes tied to holes, yet am strong as iron.
You saw me where I never was and where I could not be. And yet within that very place, my face you often see.
I don't have eyes, but once I did see. Once I had thoughts, but now I'm white and empty.
In buckles or lace, they help set the pace. The farther you go, the thinner they grow.
I appear in the morning. But am always there. You can never see me. Though I am everywhere. By night I am gone, though I sometimes never was. Nothing can defeat me. But I am easily gone.