The anniversary volume 230 of the Suhrkamp Library is a thoroughly philosophical book. Ludwig Wittgenstein (1889-1951) - regarded in the Anglo-Saxon world as the greatest philosopher of the 20th century, while discussions about him are just beginning here - draws a conclusion in this book. He poses the question: What and how can we know? What fundamental certainties exist in our language, in our thinking, for only if we know them can we speak to each other and understand one another. The notes aim at the limits of our experience and the possibility of recognition.