Joy can't exist without suffering.

But you do not have to experience a feeling to fully enjoy its opposite.

Define "fully"

I can't.

Source? I keep seeing this thrown around, and I really don't see how it follows. Do you really think people can't just be happy, that they need suffering in their lives, or knowledge of someone suffering? Perhaps we're operating under different definitions of 'suffering', but I'd be really interested to hear a good case study on this.