German scientist and geographer Johann Gottlieb Georgi (1729-1802) discusses earlier failed theories as to the identity of Prester John and offers his own argument: that Prester John and the Dalai Lama are the same person. He documents these ideas in his 1780 Russia, or, a Complete Historical Account of all the Nations which Compose that Empire.

Georgi begins his passage by citing earlier accounts of Prester John that proved incorrect, including those of John of Plano Carpini, William of Rubruck, and Marco Polo. After discussing the failures of the Portuguese to correctly identify Prester John, Georgi offers his theory (qtd. in Brewer, pp. 267-279):

But we must first proceed to give some accounts of Dalai Lama. He lives in a pagoda on the mountain Potala, which, according to the Jesuit Gaubil, is under 290 6' northern latitude, and 250 58' western longitude from Pekin [i.e. Beijing].

His followers explain the nature of his immortality in the following manner: that his soul, afier the death of his body, passes into another human body which is born exactly at that time, and this man is the new Dalai Lama. (Others relate that they keep a young man in the pagoda during the life of the Dalai Lama, who is to succeed him).

Almost all the nations of the East, except the Mohammedans, believe the metempsychosis as the most important article of their faith; especially the Indians, the inhabitants of Tibet, and Ava [?], the Perguans [?], Siamese, Mongouls, all the Kalmucs [Kalmyks], and the greatest part of the Chinese and Japanese. According to the doctrine of the metempsychosis, the soul is always in action, and never at rest· for no soonef does she leave her old habitation but she enters a new one. The Dal~i Lama being a divine person, he can find no bener lodging than the body of his successor; or, properly not the 50u l1 but the Fo residing in the Dalai Lama which passes into his successor...

...The name Pretre Jean, or Juan, was mistakenly heard by the first Europeans that visited tbese regions. And their fancy working upon it, formed many extravagant ideas which were received and cherished in Europe. These travellers perceived a certain resemblance between the sound of a word in the Mongolian and Tibetan languages with that of a French, Italian, and Portuguese word. Unused to the study of languages, they imagined that such words as had a similar sound must have likewise the same signification in the language of Tibet and of the Mongouls which they bore in some of the European. This idea being once received, many fantastical etymologIes and fables naturally arose, as that about a certain Indian Johannes Presbyter, etc.

Now, if we can admit that the missionaries of the Nestorians came into these countries (which almost every competent judge in such matters will allow) then the Nestorian patriarch and Prester John are one person; at least according to the rules of etymology. And this Prester John being a Christian, he must have been the Catholicus of the Nestorians; or perhaps only a bishop sent by the Catholicus, who in these distant regions assumed a greater title than was strictly due to him. In the pursuit of these enquiries we shall find this Prester Jobn, or this Nestorian Catholicus, to be likewise one and the same with the Dalai Lama...

...All these circumstances seem sufficiently to prove that the Catholicus, Preste Gehan, and Dalai, are only one person.