"They all know the truth, that there are only three subjects ..." — Marlena De Blasi quote meaning

They all know the truth, that there are only three subjects worth talking about. At least here in these parts," he says, "The weather, which, as they're farmers, affects everything else. Dying and birthing, of both people and animals. And what we eat - this last item comprising what we ate the day before and what we're planning to eat tomorrow. And all three of these major subjects encompass, in one way or another, philosophy, psychology, sociology, anthropology, the physical sciences, history, art, literature, and religion. We get around to sparring about all that counts in life but we usually do it while we're talking about food, it being a subject inseparable from every other subject. It's the table and the bed that count in life. And everything else we do, we do so we can get back to the table, back to the bed.