Time warp Mill

There's this funny passage on page 49 of Utilitarianism. John Stuart Mill claims that "practiced self-consciousness and self-observation, assisted by observation of others" will show that

desiring a thing and finding it pleasant, aversion to it and thinking of it as painful, are phenomena entirely inseparable or, rather, two parts of the same phenomenon – in strictness of language, two different modes of naming the same psychological fact; that to think of an object as desirable (unless for the sake of its consequences) and to think of it as pleasant are one and the same thing; and that to desire anything except in proportion as the idea of it is pleasant is a physical and metaphysical impossibility. (49)

I thought it was cool that Mill seemed to be affirming the necessity of pleasure at the thought of B for desiring that B, just like I do. But what really tickles me about the passage is its close resemblance to contemporary views about semantics and metaphysics. Just like Putnam with water and H2O, Mill sees one object with two names, posits an a posteriori identity, and asserts that having one thing without the other is metaphysically impossible. I know he's regarded as an early direct reference theorist, but I'm pretty surprised to see him making moves that look so Putnam. The only difference I can see is that water has a hidden essence while desire seems to have an unhidden one, but after reading Justin on natural kinds, I don't know whether any semantic or metaphysical conclusions follow from this.