Some brief highlights from The Birth of Hedonism, which I read and highlighted a few years ago....
From chapter 3.4. The Cyrenaic Theory of the Experiences:
their most fundamental set of doctrines concerns the division between their experiences (pathē) and what causes those experiences.
...the Metrodidact... explained that there are three states in our constitution. In one, which is like a storm at sea, we feel pain. In another, which is similar to a smooth undulation stirred by a favorable breeze, we feel pleasure (for pleasure is a smooth motion). The third state, in which we feel neither pain nor pleasure, is in the middle and is like a calm sea. And he used to say we have perception of these experiences alone. (SSR 4b.5 = Eusebius PE 14.18.32)
The most straightforward reading of this terminological shift is that by “these experiences” (pathē), Eusebius means the experiences of our own states: it is solely of these that we “have perception.”
Whether the Cyrenaics’ own term was “perception,” “knowledge,” “apprehension,” or something else again, its meaning is tolerably clear from our sources. This is that our sensations of vision, hearing, taste, and touch do not vouch for whatever they appear to represent; they only vouch for themselves, and they do so inwardly, unmistakably, truly, and incorrigibly.
Cicero testifies to their inwardness by distinguishing the “inner touch” from all our exterior sensations. We have interior contact with our pleasure and pain, just as we have interior perception of our own yellowing, burning, or embittering. Plutarch employs similar rhetoric in saying,
These men placed the experiences and appearances in themselves; they didn’t think the proof from these sufficed for the confirmation of real things. As if in a siege, they withdrew from what is outside and locked themselves into their experiences. (Mor. 1120c–d = SSR 4a.211)
But the Cyrenaics do not believe we can work through these disagreements and thus reveal the truth about external reality. They not only want to argue that we are less certain about the external world than about our own experiences, they want to argue that that we cannot know external reality at all.
This is a pretty comprehensive book for anybody interested in the Cyrenaics. There are some nuances separating various Cyrenaic schools which the book examines; as it's been a while since I read it, I'll shy away from getting into any detail in these matters.