Full Idea
Numbers, the Homeric gods, relations, chimeras and four-dimensional space all have being, for if they were not entities of a kind, we could not make propositions about them. Existence, on the contrary, is the prerogative of some only amongst the beings.
Gist of Idea
Many things have being (as topics of propositions), but may not have actual existence
Source
Bertrand Russell (The Principles of Mathematics [1903], §427)
Book Reference
Russell,Bertrand: 'Principles of Mathematics' [Routledge 1992], p.449
A Reaction
This is the analytic philosophy account of being (a long way from Heidegger). Contemporary philosophy seems to be full of confusions on this, with many writers claiming existence for things which should only be awarded 'being' status.