首楞嚴義疏注經 2.33

2.33

何直，猶不但也。此以一日為限，日日更化，不但約月。已上從寬至狹四限觀察無常之相，猶是麁浮，未為微細。

'Why merely' is like saying not only. This takes one day as the interval: day after day it alters and transforms, not only in terms of months. The above contemplation of the characteristics of impermanence across four intervals, from wide to narrow, is still coarse and superficial, not yet subtle.