Full Idea
It is obvious that an imagined world, however different it may be from the real one, must have something - a form - in common with it.
Gist of Idea
An imagined world must have something in common with the real world
Source
Ludwig Wittgenstein (Tractatus Logico-Philosophicus [1921], 2.022)
Book Reference
Wittgenstein,Ludwig: 'Tractatus Logico-Philosophicus (Pears)', ed/tr. Pears,D. /McGuinness,B. [RKP 1961], p.7
A Reaction
It is clear that Wittgenstein had a concept of possible worlds close to the modern view.
Related Idea
Idea 23465 The 'form' of an object is its possible roles in facts [Wittgenstein]