Quite early one morning, when St Ives was sleeping, I took a walk along Porthmeor beach. Although the sun was up, the moon still hung in the sky and I started to think about what the world looks like from space. Orbiting astronauts see just solids and liquids, patches of land and puddles of water. Back on earth, though, the sea's a trickier visual prospect. Named after an interstellar telescope, the hero of Italo Calvino's novel Mr Palomar (1983) attempts to contemplate a single wave. But, as Calvino points out, 'you cannot observe a wave without bearing in mind the complex features that concur in shaping it and the other, equally complex ones the wave itself originates' and Palomar leaves the beach a squirming ball of frustration. What he didn't realize is that the sea works like poetry, and poetry doesn't stand still.
Ian Hamilton Finlay's maritime work takes a different approach. Docked at Tate St Ives, it seems as though his prints and objects contain the whole history of the sea, from triremes to aircraft carriers. These floating fortresses are a fixture of Finlay's iconography, elemental celebrations of rough waters, fiery torpedoes, soaring jets and landing strips. One appears in the silkscreen The Divided Meadows of Aphrodite (1975), its diagrammatic deck halved by a ribbon of runway. As in much of Finlay's work, the piece's title is integrated into the image. Appearing twice (once in English, once in classical Greek), the words form waves above and below the carrier, the gravestone script promising a watery end. Land and sea, past and present, love and war - Finlay's concerns are pretty clear; although he'd rather watch myths ebb and metaphors flow than reach anything you might call a destination. The pastoral title evokes the grasslands of the classical afterlife, but it's a meadow marshy with sexual wetness, the open-thighed divide of the goddess of love. Moisture takes us back to the Styx (the river separating Elysium from the mortal realm), though it also reminds us of Aphrodite's briny birth and her journey to Cythera in a nautilus shell. This gets us thinking about shelling enemy aircraft, the crustacean curves of female genitalia and the sound of the ocean heard deep within a sea shell. Like waves lapping on to a beach, the imagery just keeps coming, a single idea generating another, then another. It's the kind of thing that would give Mr Palomar a nervous headache, but there's an incredible energy to Finlay's approach. His simple silkscreen becomes a sea of stories, in which sex and death mingle and ancient myths attain unexpected buoyancy.
For all its brainy wordplay and classical allusions, there's a bright-eyed romanticism in Finlay's work. We can see it in the great rainbow of Ark/Arc (2002), an installation in which the words 'Ark' and 'Arc' are linked by a curving spectrum of colour. The piece connects the end of the deluge with the Ark of the Covenant, Noah's boat with Abraham and the image of the rainbow with a benign, protective God. Gleaming in the sunny gallery, it's as if this diagram of verbal and visual coincidences adds up to some kind of guarantee that the almighty will make everything OK. A blanket patched with a square of red fabric, A Heart Shape (2002) feels pretty hopeful too. Its soft folds awaiting some shivering sailor, the blanket's repair work is weirdly moving. When we patch something we mend it, but we also adorn it and confirm its worth. Patching is a lot like loving someone, and Finlay's care-worn swatch of fabric seems to embrace the whole world. More melancholy are his four Rose Benches (2002), garden furniture inscribed with ships' names and docking details. Sitting somewhere between arbour and harbour, they're the perfect perch for some sailor's pining sweetheart. But their chunky oak beams are too heavy to float and our minds turn to the shipwrecked Mary Rose and memorial benches in wind-blown parks. Suddenly, the poetry of the Rose Benches starts to sound like a lament.
In many ways Finlay's work is an odd prospect. It's Conceptual, sure, but it's got a neoclassical clarity that seems out of step with the smudgy relativism of the modern world. His lyricism seems unfamiliar too, belonging not so much to the past as to somewhere outside history. Maybe this is appropriate, given that he deals in eternal things: love, war, myths, faith and, of course, the sea - what could be more timeless than that?