Some quotes from Parmenides, because reading Plato is always a good idea.
[Introduction] “The Platonic ideas were… in some passages regarded as absolute and eternal, and in others as relative to the human mind, existing in and derived from external objects as well as transcending them.”
Socrates: “If [someone] were to show me that the absolute one was many, or the absolute many one, I should be truly amazed.”
Parmenides to Socrates: “Similars… become similar, because they partake of similarity; and great things become great because they partake of greatness; and… just and beautiful things become just and beautiful, because they partake of justice and beauty.”
Socrates: “And when we put them together… and say ‘one is’, that is equivalent to saying ‘partakes of being’?”
Parmenides: “If one is, number must also be… But if there is a number, there must also be many, and infinite, multiplicity of being; for number is infinite in multiplicity, and partakes also of being.”