The image that is evoked by Logion 96, of the leaven that makes large loaves of bread, is really about the fact that the Kingdom represents something that exceeds our wildest imagination. In the Course we find this discussed in other ways, such as the difference between grandeur (of spirit, and our true nature), and grandiosity (of the ego - which is really the superiority complex covering over an inferiority complex). Our reality as immortal spirit is completely beyond what we can grasp within the ego mind, and hence there is always the emphasis in the Course on our relationship with our Internal Teacher, just like we find emphasis in the early Jesus literature on "following" him.
The life of the ego, is an existence of littleness, of scarcity, and of limitation. And the teachings of Jesus are nothing but an invitation to wake up from that dream of limitation, to our true reality as spirit, which is beyond our wildest imagination, and he invites us to invite him to lead us up to the level where he is.
In you is all of Heaven. Every leaf that falls is given life in you. Each bird that ever sang will sing again in you. And every flower that ever bloomed has saved its perfume and its loveliness for you. What aim can supersede the Will of God and of His Son, that Heaven be restored to him for whom it was created as his only home? Nothing before and nothing after it. No other place; no other state nor time. Nothing beyond nor nearer. Nothing else. In any form. This can you bring to all the world, and all the thoughts that entered it and were mistaken for a little while. How better could your own mistakes be brought to truth than by your willingness to bring the light of Heaven with you, as you walk beyond the world of darkness into light? (ACIM:T25.IV.5)