The Ten Fetters: #4, Sense Desire. Sorry, Hedonists.
The fourth and fifth fetters are the same as the first two hindrances: sense desire (kāmacchanda) and ill-will (vyāpāda). After the first three fetters are unbound with the attainment of stream-entry, these next two simply weakening (or maybe it's not so simple) constitutes the next stage of awakening: once-returning.
With stream-entry you are inevitably bound for full liberation in seven lifetimes at the most, and the weakening of these next two shortens that to a single subsequent lifetime as a human. Whether or not you take that metaphysics literally, the sense is that when we really make a dent in the deep ego patterns that manifest as sense desire and hatred, permanent liberation is substantially closer. These are among the most impactful of saṅkhāras—unconscious habits that drive our intentions and actions.
As you know, I think it's important to understand eros without patriarchal or inherited religious moralism, especially for those of us who are not monastics practicing celibacy and poverty as core renunciations. How can we think about sense desire as a hindrance and a fetter without falling into a Western cultural habit of body negativity, sexual repression, or an unhealthy preference for dissociation? We thread the needle tonight.