Tea is the marriage of tea-leaves and hot water. Many particulars may be debated about the water and its heat, the quality and quantity of the tea, the receptacles it is made in, and the other substances to be introduced subsequently, such as milk, sugar or lemon. But the key to tea is an encounter between water and tea-leaves.
Sir Kenelm Digbie was an English courtier and diplomat, not to mention a Catholic, a Jacobite, a pirate, and a founding Fellow of the Royal Society. Anthony Wood called him ‘the magazine of all arts’. He had an extraordinarily wide interest in beverages and preservatives, part of his curiosity about regimen, a system of eating yourself healthy. After his death, his book of recipes was published as The Closet of the Eminently learned Sir Kenelme Digbie Kt. Opened, printed in London in 1669. Digbie was very curious about tea, as one of the new beverages from the East that seemed to have mysterious and efficacious powers over human bodies.
One of his odder recipes concerns one from China for a preparation of tea. He claims he was told about it by Edmund Waller, the tea-fancier and poet, who learned it from a Jesuit missionary who visited London in 1664. John Evelyn reports in his diary — his Kalendarium — that he met with a Monsieur Tomson, a Jesuit in London, on 22 June 1664. Tomson was in possession of a large collection of rarities sent from the Jesuit mission in China, including rhinoceros horns, a vest made of gold cloth, a girdle spangled with rose-red rubies, and knives of uncommon sharpness.
Father Tomson reported that the Chinese sometimes take their tea in this manner:
To near a pint of the infusion, take two yolks of new laid eggs, and beat them very well with as much fine Sugar as is sufficient for this quantity of Liquor; when they are very well incorporated, pour your Tea upon the Eggs and Sugar, and stir them very well together. So drink it hot.
The hot tea, when it meets the beaten egg and sugar, causes the eggs to coagulate and thicken. Monsiegnor Tomson suggested that this preparation was for ‘when you come home from attending business abroad, and are very hungry, and yet have not conveniency to eat presently a competent meal’.
Twenty years later, on April 14 1684, the great English philosopher John Locke encountered a Mr Bremen at a friend’s house in Holland. Bremen had lived for eight years amongst the ‘Japaners’, as he called them, presumably in the Dutch factory at Nagasaki. He too suggested making a caudle of tea with eggs. His preparation specified that:
He beat the yolkes of eggs with sugar candie in a basin and then powerd in it the hot infusion of Thee always stirring of it. When it was well mixed makeroons were broken and sopd in it and rose water added. This was a very pleasante drinke or rather caudle. The preparation was about 3 eggs to ½ a pint of the liquer.
According to the OED, a caudle is a warm drink consisting of thin gruel, mixed with wine or ale, sweetened and spiced, given chiefly to sick people.
As Locke notes, this is a ‘very pleasante drinke’: warm, sweet and thick with eggs, the tea providing just enough bitterness and astringency to flavour the mixture. The same method is used to make certain sauces in French and Italian cuisine: sabayon and zabaglione amongst them. I once had green tea sabayon alongside apple tart and passion-fruit jelly at Bistrot Bruno Loubert, in Clerkenwell, London, and it was more than pleasant. Bruno was not revealing his recipe, but experiments at home show that this works well.
Tea with Eggs, or the Jesuit’s Green Tea Caudle (1664)
3 egg yolks, fresh and at room temperature.
½ cup caster sugar.
½ pint hot green tea (strong but not steeped more than 5 minutes).
In a stainless steel bowl, whisk the yolks and sugar until light and fluffy. Then slowly add the green tea, mixing all the time. If the mixture becomes cold, place the bowl over a simmering pan of water, whisking all the time. When fluffy and mixed up, pour into bowls or mugs and serve. It should be warm, sweet, green and taste of tea.
If you want to make Locke’s caudle, crumble crunchy almond macaroons (amaretti) into the cups before pouring in the caudle. Serve one amaretti on the side.
 The Closet of the Eminently learned Sir Kenelme Digbie Kt. Opened (London: printed by E. C. for H. Brome, 1669), pp. 155-56
 Kenneth Eastham Dewhurst, John Locke, 1632-1704, Physician and Philosopher. A medical biography. With an edition of the medical notes in his journals, Publications of the Wellcome Historical Medical Library. New series. vol. 2. (London: Wellcome Historical Medical Library, 1963), p. 241.