The prodigious expansion of the progressive (be + ing periphrastic form, where be is at the same time the copula and a statement of existence) was a major feature of the modernization of the English verb system in the 19th century, when its frequency quadrupled. A survey (1787–1880) of the collections of private letters from 22 people, most of them famous writers, reveals that linguistic factors played a relatively small quantitative role in this development, whereas a clear correlation is found with two sociolinguistic factors: gender and intimacy. Frequencies are consistently higher for women than for men, and they increase with more intimate correspondents. Some parallels with biographical and literary data suggest that the Romantic vision, in a wide sense, may have contributed to the rise of this concrete, expressive, warmer existential form.