Philosophy forgot to ask what "being" itself actually means

Heidegger's opening provocation is that the entire history of Western philosophy, from the ancient Greeks onward, has treated the question "what does it mean for something to be?" as either self-evident or unworthy of serious investigation, focusing instead on cataloguing particular kinds of beings — objects, substances, causes — while leaving the underlying concept of being itself unexamined.

He argues this omission isn't trivial; it's a foundational gap that distorts everything built on top of it, because philosophers have unconsciously assumed a specific, often overly simple picture of being — treating it like a static property objects simply have — without ever justifying that picture.

His project is to reopen this supposedly settled question and argue that answering it properly requires starting somewhere unconventional: not with objects in the world, but with the one entity that can actually ask the question in the first place, namely a human being wondering about its own existence.

Takeaway: the most basic assumptions in any field are often the ones nobody thinks to question.