Faith and Reason: Measure the day, mark the week: 'Man is a two-legged featherless animal that shops': Margaret Atkins updates Aristotle's description of humanity to consider the way we regard time today.

SUNDAY is dying, and we still don't see why this matters. The way that we organise our time is not only practical, but also symbolic. The meaning of our days, our weeks, our seasons, reveals who we think that we are.

Our predecessors used rich and complex systems of meaning to describe their times: prime, terce and sext; market day and wash-day; lambing time and harvest-tide; Shrove Tuesday, Lady Day and All Saints'. These systems were intertwined: at Michaelmas you paid your rent; on the feast of St Martin you killed your goose. A time brings with it the activity that gives it meaning: when we are is when we do.

In a world without electric light and central heating it would have been obvious that most of our times were given us by nature. The day rose with the sun, and grew and shrank with the sun through the year. The moon provided a regular cycle that was handy for marking meetings and festivals. (Soon this was artificially remodelled to fit with the solar year.) The year itself beat with the strongest pulse of all, dictating the rhythm of work and rest and comfort. This most basic year, the natural and agricultural, became overlaid with other years, educational, commercial, legal and religious. The calendar was a glorious record of jostling human activities.

And into all of this, half submerged by it all, slid the week. Unlike the others, the seven-day cycle was not given by nature. It carried no natural set of meanings. Some societies have done without a regular cycle between the day and the month. Others have experimented with four-, five- and even eight-day weeks. Such cycles are cultural, conventional. They work because they are given meaning: every fifth day is market day, perhaps; or every seventh is the Sabbath.

The week is conventional, but it is not 'mere' convention. Symbols function at a deep and important level. When we carelessly cast off a symbol, we ought to ask what else we are throwing away. The two previous attempts to kill the week were far more deliberate than our own. The French revolutionaries reformed the week into 10- day cycles in the name of 'reason' and against Christianity. The Russian revolutionaries attempted a five-day cycle of working shifts in the name of economic efficiency (on any one day, one-fifth of the workforce had their holiday). Both attempts were spectacular failures. The old rhythms stubbornly reasserted themselves.

We, perhaps, will at last succeed in laying the week to rest. If so, we will do so by default. If Sunday becomes just another day when some work and others don't, this will not happen in the name of anything. It will happen in the name of nothing. It will happen because we had nothing that mattered enough to fill up our time with. Unlike the quiet masses who resisted the Revolutionary 'reforms', we will not have cared enough about our week to keep her alive.

When we did care, it was because time was something that took its meaning from the way that we shared it. Lighting helped to distance us from the natural day, heating from the natural year. But more subtly than these, it was numbers that detached time from nature, and thus eventually from communities. When clocks were invented, time became something abstract, detached from the rhythms of the sun, the farmer's day, the monk's round of prayer. Hours were turned into identical anonymous units; before clocks, they had lengthened or shortened with the length of the day. . Now, for the first time, we could 'save' time, or 'waste' time. Today's units could be stored up and used instead next week. Individuals could 'clock up' their own hours of work or of 'free' time.

Now the same is happening to the week. Days have become detached from the cultural cycle of the community. There is nothing that we do together on Sunday, or for that matter on Michaelmas or St Martin's. Sunday is no longer a feast day, filled with positive content. It is something negative, 'leisure', defined as absence from work.

A festival belongs to us. Leisure belongs to me or to you. So why can't I do with it as I want? Why can't I waste it, or save it? Why can't I work on a rest day and earn a different day off? (A day off, note, not a holiday - a holy day - when something is actively celebrated.) There is nothing positive, nothing meaningful, nothing shared to get in my way.

The week is a cultural and religious cycle. it has become so deeply a part of us that it is hard to remember that its rhythms are not natural. Originally, though, it was part of a great and daring international experiment, an experiment in dedicating time primarily to God. The time that was dedicated to God, however, was always human time; and so the rhythms of the farmer, the teacher, the lawyers were interwoven with those of the community at prayer. Communal and religious life shared their meaning with each other (think of the Harvest Festival). The individual's private ambitions and private pleasures were inevitably set in the fuller context of communal and sacred time.

I began by mourning the dying patient. Is the grief premature? For most of us, surely, the week still shapes our lives. We are cheerful on Fridays - so the sociologists tell us - sociable on Saturdays, sleepy on Sundays, and suicidal on Mondays. We still mark our week by its highlights: the film, the football, the family. The week struggles on then, but it is a week whose peaks are mostly privatised pleasures. It is no wonder that the law, the protector of our common life, will no longer protect the week.

Our clocks and our calendars, our cycles and our seasons, reveal the nobility - or the hollowness - of our collective ambitions and ideals.

Do we measure our day by sunrise, by vespers, or by Neighbours? Do we mark our week by market day, by the resurrection, or by the pub? If we turn our Sabbaths into shopping days, we will be stating clearly who we are. We will have rejected two and a half millennia of self-identification as creatures who worship and who celebrate together. Now, we will publicly declare, we are defined as homo consumptor: man is a two-legged featherless animal that shops.