Therefore, let man look at his food.
Let the human consider his food
Let the human reflect on the food he eats
Then let man look at his food -
So the human/mankind should look/watch to his food
Let man look at his very food that sustains his life [it does not grow up in the super market]
So man must look at his food
Now let man look at his food
So man should look at his food (and ponder)
Therefore let such a person look at his food
Then let man look at his food