Now how was Abraham to manage to get a foundation laid for this mighty kingdom?
Was he to get it all through one wife?
Don't you see how ridiculous that is?
Sarah saw it, and Sarah knew that unless seed was raised to Abraham he would come short of his glory.

So what did Sarah do?
She gave Abraham a certain woman whose name was Hagar, and by her a seed was to be raised up unto him.

And was that all?
No.

We read of his wife Keturah, and also of a plurality of wives which he had in the sight and favour of God, and from whom he raised up many sons.

There, then, was a foundation laid for the fulfilment of that grand promise concerning his seed." He peered again into the fire, and added, by way of clenching his argument: "I guess it would have been rather slow-going, if the Lord had confined Abraham to one wife, like some of these narrow, contracted nations of modern Christianity.