The Elements of Style is an American English writing style guide. It is one of the most influential and best-known prescriptive treatments of English grammar and usage in the United States. It originally detailed eight elementary rules of usage, ten elementary principles of composition, and "a few matters of form" as well as a list of commonly misused words and expressions. Updated editions of the paperback book are often required reading for American high school and college composition classes.
Similar to this, but with even less justification, is the use of the plural pronoun with the antecedent anybody, any one, somebody, some one, the intention being either to avoid the awkward "he or she," or to avoid committing oneself to either. Some bashful speakers even say, "A friend of mine told me that they, etc."
Use he with all the above words, unless the antecedent is or must be feminine.