פירוש על ברכות 4:11

I.e. the poor man (mentioned in the first Baraita) who has his evening meal early through lack of artificial light, and people generally (mentioned in the second) on the Sabbath-eve who have their supper early.

The reasoning may be simplified by calling the meal-time of the poor man A, that of people on the Sabbath-eve B, and that of the priest for partaking of the Terumah C. In this paragraph A is assumed to equal B. If, then, A is said to equal C, then B = C. But R. Meir, who adopts B, is contrasted with the Sages who adopt C, so these cannot be identical.