More yokes

Celia in chapter 1 was labelled a yoked creature.

Now Mr Vincy "felt his neck under Bulstrode's yoke." (ch 13)

Lydgate, young, and refusing to be yoked (ch 15):

He was but seven-and-twenty, an age at which many men are not quite common — at which they are hopeful of achievement, resolute in avoidance, thinking that Mammon shall never put a bit in their mouths and get astride their back, but rather that Mammon, if they have anything to do with him, shall draw their chariot.

Farebrother (ch 17) (on the difficulty of independent thought/opinion):

"But then you must be sure of having the value, and you must keep yourself independent. Very few men can do that. Either you slip our of service altogether, and become good for nothing, or you wear the harness and draw a good deal where your yoke-fellows pull you."

There's an interesting point in SparkNotes related to the idea of being yoked:

The blurred definition of "debt" carries social pitfalls. Bulstrode and Featherstone deliberately keep the matter of "debt" indistinct. They leave the question of "debt" somewhere in between its strict financial meaning and the vaguer notion of personal obligation. In this way, it never really becomes clear when the "debt" is paid.