Recently, in the previous world, I was in Athens for a job. It was the sort of job that required me to speak to people who spoke about other people, but sometimes they forgot to speak about other people and spoke about Hydra instead. They disagreed about a lot of things but they all agreed that I must go to Hydra at once. I loved being in Athens and walked each morning to the Acropolis to gaze out at the misty hills. Yet the general urging was too great, so one weekend I took a hydrofoil from Piraeus, across the glittering sea.

Perhaps it’s impossible, even with my limited classical education, to traverse the Aegean without emitting the phrase ‘wine-dark sea’. It gets repeated throughout Homer, and stock phrases helped the oral poets remember their lines, I remembered, as I repeated the phrase over and over in my head. The description has bemused scholars, because seas are generally not wine-dark, but blue or green. Some argue that Homer was colour-blind, and that this is why his sheep are purple, honey is green and the sky is bronze. Others say there’s no point picking on Homer, because all the ancient Greeks were colour-blind, which is why Xenophanes and Aristotle saw only three colours in a rainbow. Others propose that the Greeks weren’t colour-blind at all but in fact for complex geological reasons their wine really was blue. (This doesn’t explain the sheep, etc.) A few weary literalists point out that it doesn’t matter if Homer was colour-blind because he probably didn’t even exist. Only lunatics – and novelists – concern themselves with the inner lives of unreal people.

Perception is a weird thing. Lawrence Durrell saw Hydra as a ‘great horned toad’ but Henry Miller thought it resembled a ‘huge loaf of petrified bread’. Niko Ghika painted it as a series of neat white and orange squares. When I arrived it was dark. Lights shimmered on the water and it was hard to tell where reality ended and reflection began. There was a pungent smell of donkeys and I immediately got lost in a labyrinth of narrow streets. In the morning I was still pondering the loaf and the toad. Everyone talks about the light on Hydra, but sometimes there’s a very good reason why everyone talks about something. The light on Hydra is bronze and blinding. The sea was mostly green – if green means green. There were violent storms in the Aegean. I took a small boat round the bay and the waves smashing into the frangible hull felt as hard as concrete. The captain said, ‘Sit in the stern and don’t worry.’ But sometimes you have to sit in the bow and worry like anything. Otherwise, it was very peaceful on Hydra. Goats grazed in the sketchy grass and donkeys clattered up the stone steps. Everything was beautiful and windy and bright.

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After a couple of days everyone told me I should go to Mycenae, so I boarded another hydrofoil. By then the storms were over and the sea was torpid. Mycenae lies on a wild, atmospheric plain, flanked by whispering cypresses and olive trees. You walk up a great stone road towards what might have been the Lion Gate, with a shattered lintel. Miller wrote that Mycenae ‘wears an impenetrable air; it is grim, lovely, seductive and repellent’. I didn’t quite agree with him about the petrified loaf but it’s true there’s something both intimate and appalling about abandoned cities. You can take terrible liberties, step over crumbled walls and into houses that were once warm and private. I kept expecting to be rebuked by strange, angry spirits, commanding me – reasonably enough – to get out of their bedroom.

Agamemnon was king of Mycenae until he was murdered by his wife, Clytemnestra (who was murdered in turn by their son, Orestes). This charming family was possibly unreal as well. Pausanias, the author of the earliest-known travel book about the Argolid Peninsula, thought Mycenae was destroyed by its envious neighbours. Rival theories abound, involving earthquakes, volcanic eruptions, climate change, dynastic disputes, and all or none of the above. In Against the Grain: A Deep History of the Earliest States, James C Scott suggests that the great cities of the ancient world might have been emptied by pandemics. As formerly nomadic peoples moved into fixed settlements and began to domesticate animals, they became susceptible to zoonotic diseases. Contagions spread from their flocks, or were brought by visitors or by soldiers returning from distant wars. The residents of early states knew to quarantine arrivals, to isolate new cases. If an epidemic took hold, they sometimes abandoned their great cities and fled.

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Last month I took part in an annual philosophy festival called HowTheLightGetsIn. We normally convene in a field in Hay, but this year the tents were virtual, as with so many other events. I was on a panel with Simon Blackburn, Hilary Lawson and Ray Tallis. We talked about a lesser-known member of the Inklings, Owen Barfield, who wrote about perception, Homer and rainbows, among other things. Barfield proposed that the world as we know it co-evolves with consciousness; a world without consciousness is a different world altogether. We assume a rainbow is an unyielding material reality, but it’s created by the interaction of water droplets, sunlight and the human iris. Without the observer, there’s no rainbow. Meanwhile the sea might be the colour of Bordeaux or the colour of runner beans, but if there’s no one to observe it then it isn’t really a sea.

At the cyber festival, we all occupied little tiles on a screen. It reminded me of Ghika’s paintings, reality comprised of shining squares, fractured and yet somehow whole. At times, people froze mid-sentence or vanished. When you vanish from a cubist cyber landscape you only vanish to others, not to yourself. On your own screen you are still moving happily in your shining tile, but to everyone else you’ve gone. I wondered what Barfield would have made of all this. Perhaps he would have told me I needed a better laptop. After a while, it felt like being somewhere and nowhere at the same time, like being trapped in a really complicated short story by Borges, or in a petrified loaf. Or in a memory dream of labyrinths and ruined cities, where you’re trying to find the Minotaur, certainty or a way out. The sky is bronze (probably). It’s all a matter of perspective.