He admires the lowly and unloved creature and elevates it to the central metaphor of hope because, he says: "It seldom wins and when it does only by the smallest of margins. It crawls, it goes into hiding, but it keeps on, putting down its tracks on the historical landscapes, on documents and on border lines, amid building sites and ruins, far from smug theories, skirting retreats and the silt of revolutions. What is progress? Being just a little quicker than the snail."
This hymn to gradualism and the need for patience as well as passion in politics is a useful corrective to the high octane-language and the frenetic activity we have witnessed in the latest round of the peace process.
Tony Blair spoke last week of Ulster "staring into the abyss" if the deal were to fall through. Hopes for peace are relentlessly corralled towards deadlines, and when those fail, more deadlines. The IRA is already on its third ultimatum to begin decommissioning since the Good Friday agreement was signed.
Then there are the "make or break" talks, the "last ditch attempts", "going to the wire", and the inevitable intervention of an American president lecturing people steeped woefully deep in history that history will not forgive them if they miss this one and only, never-to-be-repeated chance.
Statesmen are as prone to fashion as anyone else and the setting of deadlines, whether in the Middle East or Ireland, is deemed to be essential to success. The justification sounds plausible. These things have a forward momentum, a ball which must be kept rolling, a bicycle which must be pedalled along, a train we must not miss because the alternative is unthinkable.
Ulster negotiations have a ritual of its own, as predictable as any church litany. Lo, says the British prime minister to each side, I am giving you the best deal you can get. There is no other choice but failure. There is no "plan B".
Mr Blair echoed this yesterday when he appealed to the Ulster Unionists to back their embattled leader David Trimble in accepting the outcome of the Stormont talks. After thirty years of bloodshed, Mr Blair urged, was it not worth waiting a mere thirty days "to see if it is ended"?
It is a rhetorically powerful question, but a thoroughly unrealistic proposition. Whether the IRA hand in one Armalite or three thousand within a month, there is still no guarantee that peace will break out. Mr Blair talks of the process "leading to complete decommissioning". But that is an impossible aim. There will be weapons in the hand of sectarian groups on all sides for a very long time to come.
The decommissioning that matters is the decommissioning of the will to kill, not merely the means to do so. And even if, by some miraculous run of good fortune and flexibility, the Northern Ireland Assembly and Executive is set up successfully, we would still, unfortunately, be very far from guaranteed and perpetual harmony in Ireland.
Mr Blair knows this as well as anyone else. Like all the many other British prime ministers who have sought to end Northern Ireland's Troubles, he has entered a web of moral ambiguity and a world in which the formal language of negotiation is connected only loosely to what happens back in the towns and villages, the churches, pubs and killing fields.
But wishful thinking is not always a bad thing. By creating the expectation of success and raising the spectres of untold horror if a deal falls through, Mr Blair is making it hard for those ambiguous or downright hostile to the peace process to call it all off.
Such is the dramaturgy. But Mr Blair must be careful not to exert pressure too forcefully. Mr Trimble has asked for time over the summer to persuade a sceptical and anxious grassroots about the merits of power-sharing, while Downing Street is still talking the inflexible language of absolute timetables. This is the time to slow the pace of the process and allow Mr Trimble the time to talk to his own people without the presence of a stop-watch.
In the metaphor he is prone to over-use, the Prime Minister pledged again to strain every sinew in the pursuit of a deal. Sinews were duly stretched at the weekend, sleepless nights endured by the politicians in a noble cause. The announcement of a deal headed the news bulletins. After the signing and the smiling, when the flash bulbs have popped their last, the fate of Northern Ireland will be decided by slow, small steps.
It is not true, as the pessimists maintain, that nothing ever changes and that the tribal hatreds can never be tamed. Nor is it true that the guns will fall silent in Northern Ireland if this deal succeeds. Real, lasting, reliable peace is incremental. It does not descend at the signing of an agreement or the handing out of the Nobel Prize.
By now, you may be thinking that this is a depressing, even grudging take on events when the vast majority of good people everywhere wholeheartedly wish for a positive outcome. God knows, it is something if bombs do not go off in Warrington or Canary Wharf. But it is far from a solution while the violence continues in Armagh and Tyrone.
The real vindication of the peace process is that it has revealed how much the men and women of Northern Ireland long for peace and how firmly the divided communities are united in rejection of those whose secret desire is to lapse back into the cycle of intimidation and terror.
When peace has come to Ireland, we will look back and see that it approached by degrees and with many detours and obstacles, two steps forward, one back - and sometimes the other way round. It will announce itself with a whisper, not a triumphal shout or a banner headline.
Mr Blair vowing to strain every sinew is precisely the wrong kind of image in this context. Laying aside ethnic strife is about unclenching, about letting go of myths and prejudices. It is about a generation on either side of the sectarian divide learning not to strain their sinews, not to respond to the siren lure of what the poet Seamus Heaney has called "the exact and intimate tribal revenge".
In Ireland, as in the Middle East and the Balkans, I remain on the side of the optimists - albeit the long distance runners, not the sprinters who tell you that if the finishing tape is not breasted this week, this month, this year, then all is lost. Peace will come, perhaps within 10 years, perhaps longer. As Grass says at the end of his Diary: "Only those who know and respect stasis in progress, who have once and more than once given up, who have sat on the empty snail shell and experienced the dark side of utopia can know what progress is."
The snail gets there in the end. It refuses to give us a guaranteed time of arrival.