Sforno on Genesis 41:8/ספורנו על בראשית מ״א:ח׳

1ואין פותר אותם, because they all proceeded from the premise that there had been two dreams. They did not realise that in the first part of the dream the focus was on the active causes of producing food, i.e. ploughing by the cows and threshing of the grain before it could release its kernels, whereas in the second half of the dream the focus was on appearance of the product which is converted into food, the stalks of growing corn, as well as its function, i.e. when the ears are empty there is no food.