19. And to imagine a language means to imagine a form of life.25. It is sometimes said that animals do not talk because they lack the mental capacity. And this means: “they do not think, and that is why they do not talk:’ But—they simply do not talk. Or to put it better: they do not use language—if we accept the most primitive forms of language.—Commanding, questioning, recounting, chatting, are as much a part of our natural history as walking, eating, drinking, playing.384. You learned the concept 'pain’ when you learned language.357. One might say: “‘I know’ expresses certainty, not thecertainty that is still struggling.’358. Now I would like to regard this certainty, not as something akin to hastiness or superficiality, but as a form of life.359. But that means I want to conceive it as something that lies beyond being justified or unjustified; as it were, as something animal.360.1 know that this is my foot. I could not accept any experience as proof to the contrary. —That may be an exclamation; but what follows from it? At least that I shall act with a certainty that knows no doubt, in accordance with my belief.475. I want to regard man here as an animal; as a primitive being to which one grants instinct but not ratiocination. As a creature in a primitive state. Any logic good enough for a primitive means of communication needs no apology from us. Language did not emerge from some kind of ratiocination.The remarks from the Philosophical Investigations highlight the connection between acting in human kinds of ways, mastering certain concepts, and speaking as human beings do. The remarks from On Certainty highlight the connection between acting and speaking as human beings do and conceding the truth of certain judgments.