Today's reading is in Psalms 70, 71, 77, 83, and 86.  My history with God teaches me that He is mighty, holy, and powerful.  "To this I will appeal. . ." means, given my history, I know that God is always there for me. 

"Though you have made me see troubles, many and bitter, you will restore my life again. . . ."  Psalms 71:20