The very existence of letters, their necessity for written communication, is motivated by separation. The last chapter emphasized the context of the mentor books, written to guide young people who had moved away from families to towns and cities for work in their new urban lifestyle, but the need for communication expanded globally—through empire, grand tours, travel, and exploration—during the eighteenth century. Letters were the vital means by which people corresponded during periods of separation; by which they forged and nurtured bonds; friends shared news; networks developed; courting lovers expressed their feelings; and families kept in touch. The letter ‘did not only represent or serve as a proxy for their authors, but also became material extensions of the person’; the mentor book merely personified the mentor figure, whereas the letter was the ‘embodiment of the absent sender’. They were able to evoke the presence of the writer in a way that the straightforwardly didactic mentor books could not, with their vivid descriptions of people, places, and events; the hand they were written in; the paper they were written on and how it was folded; and the drafting process being a closer approximation to the author’s stream of consciousness. They required exchange, they were fundamentally reciprocal in nature, and as ‘emanations of the self’, they were a crucial part of the dynamic process in which people’s social identities were shaped.