大般涅槃經義記 3.269

3.269

上來廣釋，「以於樂中生苦」下結，「是名初倒」總結前二，謂四對中初對到也。

The above is the detailed explanation. From 'Because within bliss one generates [the thought of] suffering' downward concludes it; 'This is called the first inversion' sums up the previous two, which refers to the arrival of the first pair among the four pairs.