Sending / Receiving
When we speak of "bringing a horse on the bit" or "of breaking at the poll" hopefully we're really talking about the same thing; namely getting the horse to travel in better balance.
Accepting the bit is just a step in the process of improving the rider's control and also the horse's way of going. The rider's leg produces "forward" i.e. "sending" while the bit is used to regulate the forward movement i.e. "receiving".
When the hands "softly limit" the forward movement while the legs continue to "send" the result is a change in balance. It's important that riders don't just crank the horse's nose in by pulling on the reins to get a head set. We teach our students to send the horse forward from the leg and receive him into soft hands... The head set will be a result of a horse moving in balance.
Remember the more you SEND the more you're able to RECEIVE.