Here "path" stands for one's behavior. "My path and my lying down" together represent everything about the psalmist. (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-merism]])
Being high and out of reach is an expression, in this case, about some knowledge that human beings cannot have. AT: "it is too difficult to understand" (See: [[rc://en/ta/man/translate/figs-metaphor]])