Mark 6:39

I believe that he ordered the people to sit down upon the grass because of what is said in Isaiah: "all flesh is grass"; that is, to humble the flesh, to make subject the arrogance of the flesh; so that each one may become a partaker of the loaves to which Jesus gave his blessing.

(Con. Evan. 2. 46) It goes on, And he commanded them to wake all sit down by companies upon the green grass, and they sat down in ranks by hundreds and by fifties. But we need not be perplexed, though Luke says that they were ordered to sit down by fifties, and Mark by hundreds and fifties, for one has mentioned a part, the other the whole. Mark, who mentions the hundreds, fills up what the other has left out.

And he commanded them to make them all sit down in companies upon the green grass. And they sat down in ranks, by hundreds and by fifties. The different groups of those reclining signify the distinct gatherings of the churches around the world, which make up one catholic. The Lord commanded them well to recline by hundreds and by fifties, so that the crowd of the faithful, both distinguished by locations and united by morals, might receive their food. Indeed, the rest of the jubilee is contained in the mystery of the number fifty, and fifty is doubled to reach a hundred. Therefore, because one first rests from evil work, so that later the soul rests more fully in thought, some recline by fifties, others by hundreds, because there are some who have rest from corrupt actions, and there are some who already have rest in mind from perverse thoughts. They also reclined well on the green grass. For it is written, All flesh is grass (Isa. XL). And those reclining on the green grass are fed with the Lord's food, who, through the zeal of continence and trampling down the allurements of carnal desires, devote themselves to listening and fulfilling the words of God.