法華文句記 3.23

3.23

問如文，答中通明異常故也。引《大經》證，如文。次「若言」下約教，雖具列四，對昔四喜不同，於今純一實喜無復差別。人天等四皆云動者，權為實動故也。

The question is as in the text. The answer generally clarifies that it is because [this joy] is extraordinary. Quoting the Mahāparinirvāṇa-sūtra as proof is as in the text. Next, from 'if one speaks of' onward, it explains according to the teachings; although it lists all four, compared with the four joys of the past, they differ: now there is only pure, unadulterated, real joy, without any further distinction. That the four, such as humans and devas, are all said to move is because the provisional moves for the sake of the real.