Does the idea of matter have a form?
Plato opposes the «IDEA» that has a form and is always perfect to the «MATTER» which is formless and always imperfect.
The problem is that, then, he must have an «idea of matter».
But the idea of matter must be formless, because ideas are perfect. But then we have an idea that is formless, and it taints the form of the realm of ideas.
Either ideas and matter never ever touch (and then the distinction is utter useless, for it makes no difference whatsoever) or their touching melts the very division (and thus makes it useless a fortiori).
Platonism is useless.