If you've never been published before, you're an 'unknown quantity', so you're going to have difficulty selling your first novel.
('chiefly US') The 'big unknown' [=the important thing that everyone would like to know] is how investors will react.
A 'fear of the unknown' kept her from changing jobs.
(..) was to die sword in hand, and enter Valhalla... where a hero's welcome awaited them... from the god Odin. The compass was unknown... and they could steer only by the sun and the stars. Once fog closed in, they were left helpless and blind. After all, the earth was flat. (..)1958 The Vikings