Often we see recipes where specific types of meat are required. One beef pie calls for "fat beef" in order to help add to the moistness that baking alone wouldn't impart to the dry meat. Similar applications of logic led to the belief that wild animals, through spending their time outside, and getting more sun and exercise, were warmer than their domesticated counterparts. Wild boar was therefore "better" than domesticated pig. Additionally, it was felt that old animals were inherently drier than younger ones. Female animals moister than male ones. The presence of capons - castrated cockerels - (often "fat capons" in recipes) alludes to the fact that while old cockerel meat might be expected to be dry, castration had helped to preserve their "femininity" and thus moistness, and this temperament could be aided by specifically requesting fatness in the recipe.
So where did the church stand on cooking? It was always seen that meat, through its warming nature, naturally led to temperaments (both sanguine and choleric) which were inherently sinful and harmful to the soul. This led to the church to the obvious belief that fast days - as proscribed by the church to improve morals - should be preferably meat free, and reliant on cooler foods such as fish.
In 1256 Ralph of Lenham wrote a treatise on fasting (the details of which may or may not have been common English practice) and how these connected to the seasons. He noted fast days (days of no food, not just meat-free days in this instance) on the Wednesday, Friday and Saturday of the first week of Lent and Pentecost, and the same days of the week following Holy Cross day (September 14th ) and St Lucy's day (December 13th ). He said:
"We must fast in order to pray to God that he temper that humour that we have within us, that temperament which most closely resembles each season and its temperament".