yes i think that's crucial to understanding S.'s argument. just as the power or principle of speech is logically prior to any particular thing that can be spoken, so there is a principle of thought, which precedes any propositional content. the priority may be grasped as temporal precedence but the logical precedence is more important. and, in the same way that the principle of speech cannot be spoken, so the origin of thinking cannot itself be thought.
can you say more?
yes i think that's crucial to understanding S.'s argument. just as the power or principle of speech is logically prior to any particular thing that can be spoken, so there is a principle of thought, which precedes any propositional content. the priority may be grasped as temporal precedence but the logical precedence is more important. and, in the same way that the principle of speech cannot be spoken, so the origin of thinking cannot itself be thought.