The Chiastic structure
Look at the D pair. The Psalmist communed within his heart, trying to find an instance when Adonai forgot to be gracious or shut up His compassion. He realized that there is no such instance – YHVH changes not. When his tears did not cease, he was thinking, perhaps subconsciously, that the right hand of the Most High could change. That lie that had slipped in, became his weakness. So what did he do in response? Instead of meditating on all his trouble (1C) he began to meditate on the work of YHVH (2C) – His greatness, His glory, and that His promises hold fast. Let us do the same!