WHEN we read about the past - The Iliad, for example, as I've lately been doing - what do we hope to learn?

Not merely a knowledge of the military procedures of pre-Hellenic Greece, surely - although you certainly learn a good deal about archaic armour, battle strategy, ships, and the ancient arts of hospitality, in the process of reading. But we also learn a good deal of human psychology.

Some of that discovery might be novel. For example, Homer's heroes - pretty much every man jack of them - at the slightest setback sit and weep. Achilles, the poem's central figure, is always at it - deprive him of a slave girl, or put his nose even slightly out of joint, and there he is, sitting on a rock, weeping.

From this, we learn that, in the period of Homeric Greece, probably around 800 BC, it was not an anomaly to be a hero and to weep. It looks very much, in fact, as if weeping is part of what heroes did; just as they took slaves and made them their concubines, and threw young children from battlements.

Although we may learn these and other interesting "facts", I doubt it is the true source of our pleasure in The Iliad. If we read it other than out of simple curiosity, or as a kind of dutiful exercise, I suspect that we do so because - for all the ways in which it emphasises our differences from the Ancient Greeks and Trojans - it defines our similarities.

When Hector bids farewell to his wife, Andromache, and his young son, Astyanax, on the battlements of Troy, he weeps, not as an ancient hero might, but as a man who knows that to fight Achilles is to risk death, and yet fight him is what he has to do.

Equally, when Achilles learns that his dearest friend, Patroclus, has been killed by Hector, his grief and rage are entirely comprehensible to us. And when, as a consequence, he enjoins battle against his best friend's slayer, he does so knowing, because he has been forewarned, that this will lead ultimately to his own loss of life - and again he weeps, for the dolorousness of life, for the awful things we do to each other, and for the consequences that we seem unequal, as human beings, to prevent. 

THE ILIAD has two scenes which, for me, are two of the finest moments in all literature. One is when the grief-stricken Achilles, in mourning for his friend Patroclus, has the body of Hector - Patroclus's slayer - dragged round and round his dead friend's funeral mound.

The second is when the figure of Hector's father, King Priam, comes by night in a mule cart to beg Achilles to return the body of his son for decent burial.

Although these two scenes are set in a time that is wholly unlike our own, what is striking is their wholly recognisable universal quality. Achilles's senseless action is a brilliant image for the sterile yet savage patterns of anger - patterns that are reflexive, take us nowhere, and become a kind of pointless ritual.

From this, we know how wounded and mortified Achilles is. We can infer, too, that he also feels guilt because his friend was slain in his place when he refused to fight. And when the old King comes, without the trappings of state, and falls on his knees and kisses the hand of his dead son's killer, how extraordinarily human and touching this is, too. Which of us can fail to be deeply moved by it?

What interests me is how, in moments such as these, we learn something afresh that is, at the same time, wholly familiar to us. We see something about the character of Achilles - maybe what makes him a real hero rather than, like his colleague Ajax, a mere fighting machine - but we also learn anew something about humankind.

One of the things that we learn is that human nature does not change very much, and that, across time and culture, we have, as human beings, much more in common than in difference. Not a bad lesson to keep in mind in today's troubled times. 

Salley Vickers's latest collection of stories, The Boy Who Could See Death, is to be published by Viking Penguin in April 2015.