If good is a form, then it is not an idea....Plato<quoted text>
Hmmm...the essence of the rose is observed through the senses? I'm not sure what that even means, let alone whether it is true. We certainly detect the chemicals released by the rose through our senses. I wold suspect that a creature or individual with a differently built nose would not necessarily detect the rose as smelling good.
So you are limiting truth to only the raw sensory detection? In that case, we can't even tell that there is really a rose there: we only see light and smell chemicals.
The senses deals with forms. The mind deals with ideas. Understanding deals with concepts.