The Cathars were important to Luca because the rumor about noblemen looking for a lost child included that these people traveled in the company of Cathars. The Cathar practice of laying-on of hands known as the consolamentum, which they used as a baptismal right, also plays a large part for Luca, who discovers its power on his own.

Another group that tantalizes Luca is the Sethians. Sethianism is a Gnostic pre-Christian sect named after Seth, the third son of Adam. They saw Seth a divine incarnation and his direct descendants as a superior, elect group. In Immortal, Sethians are accompanied and protected by Cathars. Could it be that Luca is Sethian, and that's why he appears not to age?

By implying a relationship with heretical religious movements, Immortal provides an explanation for Luca's long life. Because Luca was separated from his parents, there is conflict, mystery, a journey. This driving idea feels secondary, however. Immortal is an extremely long narrative only loosely bound by Luca's search for his parents. Large sections of the book simply describe Luca's life in Florence and the different avenues he pursues during his long life, including medicine and alchemy. Since Luca is writing a
memoir, he starts off by telling the reader he might have lived forever
were he were not being put to the death by the Inquisition, and he often tells the importance of a situation before he recounts it, thus reducing the suspense of the
story to nearly nothing.

Regardless, Immortal is an agreeable read. Many nasty things happen in the book, but they are not discussed in gory detail, Slatton's interest being more in their emotional effect on Luca than on literal depiction of medieval horrors. Luca lives in a fascinating epoch, comes into contact with interesting philosophical and religious ideas, and befriends intriguing people. His story should be of interest to anyone who likes historical fiction or art history.