This is a word of desire.
It may seem inelastic, cataclysmic, or simply classic yet plastic; it may crackle too lightly to match the pyroclastic flow of the volcano of desire; it may seem suspended between antic and class. No matter.
This word, this adjective, comes from Greek ἀνα ana ‘back’ and κλᾶν klan ‘break’. Is it that desire can be backbreaking? Salvatore Quasimodo wrote of love as backbreaking work: “Fatica d’amore.” But no, this breaks back in another way. Three other ways.
The first thing analcastic refers to is refraction. When light comes at an oblique angle into water, or any other medium that it travels more slowly through than the air it was in, it changes angle. This is why a stick half in a pond seems to break at the surface, why a body in a bathtub seems flatter than the head that sits above the surface. The waves of light are like a marching troop who go at an angle from hard earth into a body of water: the first ones in, on one side, slow down while the others are still marching at the faster speed; as they all enter, they all slow down, but since the slowing starts at one side and moves across, it changes the overall angle of their progress.
Why is this like desire? Because desire is like water: you swim in it, it embraces you, but it slows you, it slows time, and what seems straight when seen inside it seems crooked when seen from outside. And vice versa. Eyes that look into desire see things at different angles, closer, larger. And if you are moving forward with another person, and one of you enters or exits desire before the other does, the angle will change, it will break.
The next thing anaclastic refers to is a kind of glass. Here, let me quote from the supplement to the 1753 Chambers’s Cyclopaedia, nicely supplied by the OED:
Anaclastic glasses are a low kind of phials with flat bellies, resembling inverted funnels, whose bottoms are very thin..and..a little convex. But upon applying the mouth to the orifice, and gently..sucking out the air, the bottom gives way with a horrible crack, and of convex becomes concave. On the contrary upon.. breathing gently into the orifice, the bottom with no less noise bounds back to its former place.
When desire enters you, it may have been flowing in gradually, but at some point the pressure reaches a break point and you have a realization – the arrow of cupid strikes you – and with a crack, your volume expands, you swell, the pressure is too much. Likewise, if desire flows out gradually, at some point you can no longer hold on and, with a crack, the vacuum is corrected and you are back to normal, but somewhat diminished.
The third thing anaclastic refers to is anaclasis, a little trick in Ionic verse where the long beat at the end of one foot swaps with the short beat at the start of the next, so instead of “da da DAH DAH, da da DAH DAH” you get “da da DAH da DAH da DAH DAH.” How does this have to do with love? Because it is used in “L’amor, dona, ch’io te porto” by Jacopo da Fogliano. Here, listen to it and you will hear the anaclastic metre:
Now, if your Italian is not sufficient to tell you what the singer says, read the serviceable translation posted by Piero Scaruffi at http://scaruffi.tumblr.com/page/19 (third item down). You will see this is a song of lovesickness, of a man who is strongly desirous of a woman but cannot find the words to express it. She draws back and his heart breaks. The song does not say what the lady’s name is. I will say it must be Ana. Ana Clastic. Clearly.