Tackled in pairs, with much adversarial cross-questioning, the students teased the text into manageable strands. It was, thought Dovidl, not unlike studying music with Dr Steiner, hearing him apply experience and intuition to the inner meaning of notes. There were more staves to this score, however, than in any opus he had ever seen, more possibilities of interpretation. So complete was his absorption that he yelped with frustration when they had to break for the afternoon prayer.

‘Carry on later?’ he asked Yoel.

‘Not today,’ said the Lithuanian. ‘Much tougher tractate after lunch – ritual purity. You’ll have another partner for that.’

Tuition ended at seven, but most students returned after supper to the study hall, swaying over outsized tomes until midnight and beyond. Resuming with Yoel next morning, Dovidl resolved to test him with a Cambridge conundrum about the act of creation: ‘What happened before the beginning, when God created heaven and earth?’

Yoel dismembered the proposition effortlessly. The question was founded, he sighed, on a Greek mistranslation of the Hebrew words bereshit bara – a phrase that does not mean ‘In the beginning God created’, but ‘In the beginning of God’s creation’. The act of creation is continuous, he explained, a process in which humanity is privileged to participate. Before the beginning, there was God. Should the world ever end, He will still be there.

But what, persisted Dovidl, of the idea advanced by some Christian theologians that all God created was order among elements like fire and water, which pre-existed Creation – that order is, as the poet Alexander Pope put it, ‘Heaven’s first law’? That’s irrational, said Yoel. If elements existed before God, how did He get control of them? The organisational hypothesis of Creation contradicts the fundamental Judeo-Christian belief in a creatio ab nihilo, which Jews call yesh me’ayin – something out of nothing.

‘You don’t mind me asking?’ said Dovidl.

‘Ask what you like,’ said Yoel. ‘Nothing is ruled out in the search for knowledge. You want to know whether the world is a hundred million years old, or five thousand seven hundred and ten, according to our calculations? For us, it’s not a burning issue. The Torah tells us that the world was created in six days, but those days are not literal units of time, twenty-four hours each. The Hebrew word for days – yamim – is the same as that for seas: immeasurable lengths and depths. A day can be as long as you like. Time in the Torah is relative, as Einstein well knew.’

‘Don’t you have to believe in some fixity?’

‘Our own rabbis are forever challenging the Creation passage. Some of them mischievously decontextualised the second and third words to read: “In the beginning He created God.” That, too, is no problem for us. God is sui generis. He was, is, ever will be. Now, can we get back to the question of who, exactly, owns this contested prayer-shawl? Rabbi Yossi says . . .’