The title of the present volume seems straight forward enough in its avoidance of technical terms. But just what is meant by comment clause is something which the reader must find out by reading the initial chapters of this book carefully. The term is closely related to sentence adverbial and consists of something which makes a comment on another clause without importantly being syntactically bound to it. Historically, comment clauses such as John is leaving tomorrow, I suppose or As I said, the matter is of the gravest importance are derived from syntactically linked clauses, in the latter case from I said that the matter is of the gravest importance. An essential element in Brintons tracing of such clauses through time is the formal uncoupling of comment clauses from their anchor clauses. Furthermore, they become more rigid, show less variation and do not form new combinations with other words. In this sense comment clauses share many features with grammaticalised elements: semantic bleaching and a reduction in both the internal structure of the clauses they form and in the formal links they can entertain with other clauses. This reduction often shows transitional stages, e.g. I gather in presentday English which may take a relative clause marked or may not I gather (that) John is leaving next week. Hand in hand with this syntactic slackening goes the heightened function of comment clauses as pragmatic markers which provide cohesion in discourse (p. 15). So there would appear to be a mirror-image development here: the less a clause is bound to others immediately adjacent to it the more it can provide links across elements on a discourse level. This fact is borne out by the optional placement of comment clauses sentence-finally as in John is leaving next week, I gather.