CALCULATORS have made life easier for those of us poor at mental arithmetic. For all that, I occasionally feel nostalgic for fractions: they had a clarity that decimals can never share (I speak as a non.mathematician). They made sense of division, always the most difficult of the four operations.

They were also crucial to those (hypothetical) calculations one could perform using the tables in the front of the Prayer Book. The idea that any person could calculate the date of Easter, and from that all the other moveable feasts of the Christian year, from now until the year 8500, (and indeed beyond if one follows the implications of the enigmatic ‘&c’) used to fascinate me as a child.

Why was such information given in every copy of the BCP, and what theological purpose did it serve? No vicar ever gave us any instruction, as I remember But what such numerical tables did offer was a sense of the solidity of numbers. Fractions only underlined that impression of numbers as objects. Like apples they could be divided in half, then half again, and so on.

Numbers are things. Or at least they were before calculators took them out of our hands. Now we have to turn back to solid geometry, like the ancient Greeks, when looking for the language of God and his creation. Precisely because this seems easier to imagine, it is more of a snare for the non-specialist.

You may have read that the torus is the in-shape among mathematicians just at present; it is (apparently) the most productive piece of abstract geometry. This wealth of technical research is then simplified, in the media, to the suggestion that the universe is shaped like a bagel (the popular synonym for a torus). Take it down to two dimensions, and it becomes a circle within a circle. Now expand this back into multidimensional space, and you are in business. It is almost imaginable.

This must be wrong. It cannot possibly be this easy to imagine the ‘shape’ of the universe. Numbers, unlike shapes, are more demanding, and hence more valuable. They require work; they cannot merely be looked at. Numbers, with their fractions, keep a lid on imagination. And moderate our hubris. NT