Shirley Rollinson wrote:If an English example would help :
"The black and white horses" describes a group of horses who are all piebald (black and white patches on each of them)
"The black and the white horses" describes a group of horses, some of which are black, and some of which are white.
So if the "saying, and not keeping" is to be used to describe a person who "says this" and "does not keep that", then only one "the" - ὁ - would be used.
No... This 'rule' often does not apply when the 'substantives' are adjectives, both in English as well as Koine Greek. We use phrases like "the first and second day" and "the big and small countries" all the time. Luke 6:35 has "τους αχαριστους και πονηρους" and Luke 14:21 has "τους πτωχους και αναπηρους και χωλους και τυφλους", but I couldn't find an instance with singular 'substantives' so I don't know about that case. Does anyone know any?
What I would say instead is that when one article is used for many 'substantives' joined by "και", the default meaning is that one entity (which may be plural like in Gal 4:9) is meant, but that can be easily overridden by the context if they are obviously intended to specify a number of possibilities like in the two examples above. In such cases the whole phrase sometimes behaves grammatically as if referring to one entity, but does not imply that such an entity must fit all the 'substantives' listed, such as in "The rich and poor man alike seeks happiness.".