".....I have just hinted at the reason why Providence is like a wheel; because sometimes one part of the wheel is at the top, and then it is at the bottom.Sometimes this part is exalted, and anon it sinks down to the dust. Then it is lifted to the air, and then again by a single revolution it is brought down again to the earth.....
So it is with our life. Sometimes we are in humble poverty, and hardly know what we shall do for bread; anon the wheel revolves, and we are brought into the comfort of wealth; our feet stand in a spacious room; we are fed with corn and wine; we drink of a cup overflowing its brim. Again we are brought low through affliction and famine. A little while and another page is turned, and we are exalted to the heavens, and can sing and rejoice in the Lord our God. I have no doubt many of you here have experienced a far more checkered life than I have, and therefore you can feel that your life has been as a "wheel." Ah! man, thou art strong, and great, and rich; thou mayest stand now as the uppermost part of it; but it is a wheel, and you may yet be brought low. And you, poor, who are depressed and downcast, who are weeping because you know not where you shall lay your heads—that wheel may revolve and you may be lifted up. Our own experience is never a stable thing; it is always changing, always turning round. The fly that sits now on the edge of the wheel may be crushed by its next revolution, and be brought to the dust of death the next day. The world may cry "Hosannah" to its minister to-day and the next day may say, "Crucify him, crucify him." Such is the state of man. Providence is like a wheel.
You know that, in a wheel there is one portion that never turns round, that stands steadfast; and that is the axle. So in God's Providence, there is an axle which never moves. Christian, here is a sweet thought for thee! Thy state is ever changing; sometimes thou art exalted, and sometimes depressed; yet there is an unmoving point in thy state. What is that axle? What is the pivot upon which all the machinery revolves? It is the axle of God's everlasting love toward his covenant people. The exterior of the wheel is changing, but the center stands forever fixed. Other things may move; but God's love never moves: it is the axle of the wheel; and this is another reason why Providence should be compared to a wheel......To read more go here.