It’s complicated. Love, that is. And art too. From the earliest known portrayal of physical affection (a Stone Age statuette of lovers embracing) to the opulent clinch of Gustav Klimt’s The Kiss (1907-8), the history of art pulses with passion. While cherished for the fervour of feelings they capture, works such as Rembrandt’s sweetly simmering 17th-Century double portrait The Jewish Bride (1665-9) and Auguste Rodin’s chiselled canoodle The Kiss (1901-4) are far more fraught than they first appear.

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Lean in a little and one quickly begins to detect subtle tensions unsettling the surfaces of these masterpieces. Such details, often overlooked, have the power to transform these deceptively simple depictions into something more mysterious, complex, and emotionally conflicted. “I love you as one loves certain obscure things,” Pablo Neruda once wrote, in words that aptly capture the essence of these enigmatic expressions, “secretly, between the shadow and the soul”.

At first glance, the 11,000-year-old clump of carved calcite known as the Ain Sakhri Lovers (named after the cave in the Judean desert near Bethlehem where the artefact was identified in 1933 after its discovery by a Bedouin) is disarmingly touching in its translation of fiery passion into the inert physics of cold stone. Like a crude prehistoric valentine, the 11cm (4.3in)-tall heart-shaped figurine depicts the entwinement of a couple whose bodies meld into one, as if celebrating the self-abnegating nature of love. So entangled are the two physiques, it is impossible to discern even the genders of the figures portrayed, as they crystallise into something elemental – irreducible as ore.