In a garden, a philosopher repeatedly asserts, "I know that that's a tree," while pointing to a nearby tree. This insistence on identifying the tree leads to confusion when an outsider arrives, prompting the speaker to clarify that the philosopher's actions are part of a philosophical discussion rather than a sign of madness.

This interaction illustrates an essential aspect of philosophical inquiry, showing how language and certainty can lead to pondering the nature of knowledge. Wittgenstein highlights the difference between ordinary conversation and the deeper exploration of meaning and understanding within philosophy.