Full Idea
The manufacture of beds and tables involves the craftsman looking to the form and then making the furniture. The form itself is not manufactured by anyone.
Gist of Idea
Craftsmen making furniture refer to the form, but no one manufactures the form of furniture
Source
Plato (The Republic [c.371 BCE], 596b)
Book Reference
Plato: 'Republic', ed/tr. Waterfield,Robin [OUP 1993], p.345