George Mueller's rationale

The three chief reasons for establishing an Orphan-House are: 1. That God may be glorified, should He be pleased to furnish me with the means, in its being seen that it is not a vain thing to trust in Him; and that thus the faith of His children may be strengthened. 2. The spiritual welfare of fatherless and motherless children. 3. Their temporal welfare.

It seemed to me best done, by the establishing of an Orphan-House. It needed to be something which could be seen, even by the natural eye. Now, if I, a poor man, simply by prayer and faith, obtained, without asking any individual, the means for establishing and carrying on an Orphan-House: there would be something which, with the Lord's blessing, might be instrumental in strengthening the faith of the children of God besides being a testimony to the consciences of the unconverted, of the reality of the things of God. This, then, was the primary reason, for establishing the Orphan-House. . . The first and primary object of the work was, (and still is) that God might be magnified by the fact, that the orphans under my care are provided, with all they need, only by prayer and faith, without any one being asked by me or my fellow-laborers, whereby it may be seen, that God is FAITHFUL STILL, and HEARS PRAYER STILL. (Mueller's Strategy for Showing God)

When I heard these, I saw why God saw fit to so consistently answer Mueller's prayers. Mueller lived so that God should be glorified . . . in its being seen that it is not a vain thing to trust in Him. It was this that enabled him to give so much spiritual and physical help to the orphans for whom he cared.