In his late twenties, Luke Howard wrote the "Essay on the Modification of Clouds", which was published in 1803. Howard's system was similar to the recently popularized Linnaean classification system developed by taxonomist Carl von Linne. Howard named the three principal categories of clouds – cumulus, stratus, and cirrus, as well as a series of intermediate and compound modifications, such as cirrostratus and cirrocumulus, in order to accommodate the transitions occurring between the forms. Howard's classification system applied the recently popularized Linnean principles of natural history classification. By applying these principles to phenomena as short-lived as clouds, Howard arrived at an elegant solution to the problem of naming transitional forms in nature.