Why is this? If the absence of pain is pleasurable, then shouldn't the absence of pleasure be painful, by necessity? When pleasure simply fades away, what are we left with if not pain?
We can and should through reason and logic affirmatively identify the healthy normal functioning of the mind and body (even when they are not being "stimulated") as pleasure.
Rolf , I too had a hard time understanding that Epicurus did not allow for a neutral third state; only pleasure or pain. What I have come to learn from all these Epicurean writings is that if there is no pain (body aches or mental anxiety), there is always pleasure present. You just have to tune your mind in to the small pleasures that your body is experiencing when it is just operating normally. This is also what has been described as your body operating in homeostasis, or in eustatheia (psychosomatic balance).
When sitting, standing, or walking in a neutral state, your mind can find many pleasures, just by tuning into your body's senses. The practice of "being present" is a good way to acknowledge natural pleasures; feel a soft breeze, hear a bird signing, see a beautiful photo.