ONE day," Matteo Ricci wrote in 1595, "when I was invited to a party by some holders of the first- level literary degree, something happened that gave me a great reputation among them and among all the other literati in the city." The city was Nanchang in south China, and Ricci, the Jesuit missionary (1552- 1610), told the other guests, who were in a playful mood, "that they should write down a large number of Chinese letters in any manner they chose on a sheet of paper, without there being any order among them, because after reading them only once, I would be able to say them all by heart in the same way and order in which they were written." He did so, and then, "in order to increase their wonder," Ricci recited the same characters backward, "beginning with the very last until reaching the first." The guests were astounded at this feat, "and at once they began to beg me to consent to teach them this divine rule by which such a memory was made."

Ricci was a remarkable man. Classicist, mathematician, cartologist, linguist, he represented the very best of the Catholic revival of the late 16th century which is usually called, imprecisely, the Counter Reformation. At first a law student in his native Italy, he joined the new and vibrant Society of Jesus when he was 19, was educated by fellow Jesuits in Rome, Florence and Coimbra, and came to the missions in India in 1578. Two years later he was ordained priest, and in 1583 he crossed over from the Portuguese trading colony at Macao into China proper. He stayed there for the rest of his life and thus became an unwitting witness to the penultimate days of the Ming dynasty.

One of the skills Ricci learned during his rigorous school days was mnemonics. The Jesuits took a lively interest in the various techniques of memory training, not least because their founder, Ignatius Loyola, had placed so much emphasis upon the uses of memory in the development of the Christian's spiritual life. And, more than that, Loyola's insistence that concrete images, whether fictive or real, should support one's prayer -- to evoke, for example, in minute physical detail Christ's sufferings on the cross -- meshed nicely with the systems of memory training still in vogue in Europe in his time. Ricci proved an adept student of the art; his ability to furnish the "palace" of his mind with strong images -- a statue in this corner, a divan over there -- which in turn led to deeper, inner rooms of memory astonished the intellectuals in Nanchang.

Jonathan D. Spence has employed Ricci's preoccupation with mnemonics to fashion an ingenious structure in which to bring together a history of China and Europe during Ricci's lifetime. In a genuine tour de force Spence has used two of Ricci's published works in Chinese to build a memory palace of his own; the Treatise on the Mnemonic Arts (1596) in which the Jesuit showed how Chinese ideograms, images in themselves, could be stored in the mind and ordered to promote the remembrance of scores of other things; and a kind of essay he wrote to accompany four religious pictures he contributed to a collection of Chinese calligraphy and graphics edited by a friend in Peking (1606).

Four Chinese characters, Spence tells us, and four pictures with commentary can provide the organizational principle whereby we can better understand the confrontation, as it were, between two cultures. The method, though subtle, succeeds brilliantly. The first of Ricci's image-characters, for instance, is the Chinese ideogram for war -- a picture, if one has the wit to see it, of two warriors grappling one another. With this as his starting point Spence invites us to remember how the art of war was practiced by the dukes of Alva and Guise in Italy when Ricci was growing up; how Sebastian I of Portugal, Ricci's particular patron, fought the Moors in North Africa and left his bones to bleach there under the hot sun; how the Portuguese and the Dutch battled one another for the prize of the Indies trade; how the Chinese military organization puzzled Ricci with its combination of fierceness and timidity.

Spence then moves us from the first ideogram to the first of Ricci's religious pictures, that of Peter sinking into the waters of the Sea of Galilee until rescued by Jesus. "Ricci's world," Spence writes, "was both riven and bonded by water." So "the apostle in the waves" prompts us to recall with Ricci the long voyage from Lisbon to Goa, the depredations of occidental privateers and Chinese pirates; to recall also China's huge rivers and disastrous floods and how Ricci himself lost his first Chinese house from a flood and almost lost his life in the rapids and whirlpools of the River Gan, a shock, as he wrote to the Jesuit general in Rome, "that God would choose to have me shipwrecked in a river, when I had never been shipwrecked on the seas although I had passed across so many."

In similar fashion, under the guidance of three more ideograms and three more pictures, Spence conducts us through the other rooms of the palace, and the tour is always rewarding. It suffers, however, from one very serious flaw. Professor Spence, who has written so well about various aspects of Chinese history, is not so sure-handed in preparing the European half of his diptych. Errors of fact and obscurities abound. Curious misstatements betray how little Spence understands those religious phenomena which were central to Ricci's life. Silly mistakes which a proofreader should have corrected -- Italian proper nouns misspelled and Italian accent marks misplaced -- suggest a certain confusion.

What does "a version of the earliest commentary on Christianity" mean? "St. Andrew's Quirinale" seems a peculiar way to denominate Bernini's church on the Quirinal, built 50 years after Ricci's death. The feast of the Nativity of Mary is not celebrated on September 14. The term "papal legates" reveals a lack of serious acqaintance with the constitution of the Papal States, Ricci's birthplace. Spence skews the chronology of the duke of Alva's career and adopts a polemical view of the duke of Guise abandoned by historians 50 years ago. "Reformation priests" as a term for the Protestant reformers would have startled John Calvin. "Incarnation of the Virgin" and "monastic Carthusian" are unintelligible phrases; "Benedictine friar" is a condradiction in terms. Confucius might have said that a writer should not drop a big name -- in this case John Chrysostom's -- unless he is sure of the spelling.

Spence has, in short, written a good book which with a little care might have been better. To walk through a palace with Matteo Ricci is in any event time well spent.