I have more understanding than all my teachers - Referring perhaps to those who had given him instruction in early life. By constant meditation on the law of God, he had, in the progress of years, advanced to a point beyond that to which they had arrived. He had improved upon their suggestions and instructions, until he had surpassed them in knowledge. His “design” in saying this was to set forth the excellency and the fullness of the law of God, and to show how the study of it was suited to enlarge the understanding. In early life the wisdom of teachers seems to be far beyond anything that we can hope to reach; yet a few years of study and meditation may place us far beyond them. What those teachers seemed to be to us, however, when we were young, may serve ever onward as a means of comparison when we wish to speak of the greatness of human attainments. So the psalmist says that he had now reached a point which seemed to him in early life to be wonderful, and to be beyond what he had then hoped ever to attain. He had now reached that point; he had gone beyond it.
For thy testimonies are my meditation - Compare Psa 1:2; 2 Timothy 3:15. All this knowledge he had obtained by meditation on the law of God; by the study of divine truth. The effect of that constant study was seen in the knowledge which he now possessed, and which seemed to surprise even himself as compared with the brightest anticipations of his early years.