(By Matthew S. Dryer): "Across languages, we can distinguish two types of simple sentences differing in the nature of their subjects. One sort of simple sentence involves a nominal subject, a subject consisting of a noun, plus possibly some modifiers. The second sort of simple sentence involves a pronominal subject, where there is no nominal subject and where the subject is expressed at most by a morpheme or morphemes coding semantic or grammatical features of the subject, such as person, number, or gender."