The pen is mightier than the sword, they say. The Palestinian political cartoonist Naji al-Ali certainly hoped it might be, and once drew a sword with a pen nib at its point. More characteristic of his peculiar genius for symbolism is the drawing used on the cover of this book, in which the pen stands upright, its nib doubling as a candle flame. It's a potently simple image, yet complex: the dripping wax suggests sorrowful tears; the pen's upright balance is perilously unsupported, like the Palestinian state itself; yet the backdrop of night sky, with its foully obscured moon, seems to reference the Amnesty International catchphrase about it being better to light a candle than curse the darkness.

Few artists could have been more biblically destined for al-Ali's prophetic status. Born in Galilee, he was a victim of the nakba ("disaster") in 1948 when the Jews cleared the Promised Land of its previous inhabitants. He grew up in Lebanese refugee camps and prisons, scribbling protest cartoons on the walls, and eventually found work in newspapers. From 1969 onwards, his images featured the figure of Hanthala, the barefoot child who silently watches all the evils perpetrated in the Middle East. Hanthala became phenomenally popular in the Arab world, spawning a Garfield-like industry of coffee mugs, T-shirts, keyrings, and so on. But instead of a spoilt fat cat, here was a ragged witness to atrocity and political betrayal.

Naji al-Ali steadfastly declined to make speeches, allowing his cartoons to speak for him. I don't know whether he felt, as many visual artists do, that images are diluted by "explanation", or whether he figured he might stay alive a bit longer if he (and Hanthala) functioned as mute witnesses rather than quotable demagogues. In any event, his luck ran out in 1987, when he was shot in the head outside the London offices of a Kuwaiti newspaper he was working for. Reportedly, he'd recently been warned by the PLO to "correct" his attitude to Yasser Arafat - a warning to which he responded by lampooning Arafat once more.

Al-Ali's refusal to be the mouthpiece of a political party - even one representing his own oppressed people - is somewhat compromised by A Child in Palestine. The cartoons are surrounded by an armature of text. Abdul Hadi Ayyad, in a series of introductory essays, delivers exactly the kind of rhetoric that one might expect to hear at an anti-Israel rally. The "Zionist settler project" or "Zionist entity" drives out the "indigenous" population, but the indomitable Hanthala "proudly declares that he is prepared to grasp his Kalashnikov to find the answers". Mahmoud al-Hindi adds captions to the cartoons - "Palestinian children throw rocks at the Israeli road-roller (a symbol of continued land-appropriation confiscation and illegal settlement-building)". The Iraqi poet Ahmad Matar weighs in with: "Naji al-Ali's works were like a compass which always pointed towards Truth; and that truth will always be Palestine." Why do these words make me wince in suspicion, whereas al-Ali's cartoons make me wince in sympathy? Maybe because I'm aware that Israelis have their own truth which will always be Israel, and the words therefore smell of absolutist non-communication. Or maybe it's because al-Ali's artistry nuanced and universalised the political views he undoubtedly shared with the editors of this book.

In any case, al-Ali's views evolved over time, a fact which Ayyad, in his worshipful eagerness to present al-Ali as a timeless prophet, doesn't acknowledge. Joe Sacco, whose foreword strives for diplomacy, describes how "devastated" al-Ali was by the 1982 Lebanon invasion and notes that in the subsequent cartoons, Hanthala "lost his cool". That's one way of putting it. Hanthala stops watching and starts flagwaving (literally), kicking the Israeli map and throwing rocks. The crucified Jesus yanks a nailed hand from the crossbeam to throw a stone in support of the intifada. It is in such images that one gets a sense of al-Ali being unhinged, perhaps, by the unrelenting scale of Palestinian misery, and crossing a line into the militarised defiance that made his eventual assassination inevitable. And, while it can't have been easy for the editors of A Child in Palestine to choose a few dozen cartoons from among the thousands that al-Ali produced, I can't help seeing a political agenda behind their decision to favour the more militant ones at the expense of so many of his most awesomely sad and tender images. Al-Ali, in his prime, created visionary symbols of inhumanity and the pity of war which transcended the specifics of the Israel/Palestine conflict. A few of them are reproduced here, but most are not.

For much of his working life, al-Ali insisted that it was essential to retain hope. Some of his later cartoons suggest that he found it increasingly impossible to cling to that ideal, and that instead of chronicling the endurance of the Palestinian people during a horrible phase of their history, he may have felt he was paying witness - with Hanthala-like impotence - to a gradual genocide, a final solution that would exterminate forever his boyhood dreams of homecoming. If that's so, then this book will have two legacies. First, it will introduce British readers to al-Ali's formidable talent, albeit with a selection that doesn't do full justice to his greatness. Second, and very sadly, it may serve as documentary proof that the sword is mightier than the pen.

 Michel Faber's The Fire Gospel is published by Canongate.