There is a time for Pure Obedience, "Poor Bread," which the mind and heart can try to persuade otherwise, and cause Leavening, and hence needs to be Watched and Subdued.

There will be a time, when Moshiach comes, that we will have Pure Pleasure, "Rich Bread," of mind and heart, with no need for Watching or Subduing any Leavening, for evil will have been removed from the world.

Presently, we need to have a fine blend of both, in which our mind and heart (Rich Bread) can at least appreciate that we presently need to surrender our will and have Obedience (Poor Bread). However, our mind and heart, being incapable of appreciating Torah and Mitzvot, are still in danger of Leavening. Hence we have a mixture of Rich Bread (mind and heart), which is capable of Leavening and needs to be Watched.