(4) “The Perfect Teaching”: the teachings of the Lotus Sutra and the Avatamsaka Sutra (related to that). These are the teachings that the Tiantai school specifically taught.
At this level, the most complete understanding of all, one follows the Middle Way as the ultimate truth. One understands that nirvana is the same as the everyday world.
This understanding is what is gained from the Lotus Sutra. Tiantai thus counts itself within this group.
Enlightenment on this middle path can come when one realizes that the everyday world and its afflictions are not an obstacle for enlightenment.