The use in Classical Greek of the two negatives,
un, in noun phrases is a much-debated matter in the literature on Greek grammar. Several, sometimes interrelated, factors have been adduced as decisive for the choice of negative in such cases - the predominant one being that of reference. Already a brief survey of almost any Greek text, however shows that there is a considerable overlap between the employment of
un in the uses which the grammarians distinguish. The present study investigates in a consequent fashion the use of the two negatives in noun phrases in the works of Plato. A new picture of negation in Greek noun phrases is thus gradually built up, where the interplay between
un in such cases is described in a more consistent way than by the earlier accounts.