Falstaff sees two virtues in sherry. The first is its inspirational intellectual effect:
It ascends me into the brain, dries me there all the foolish and dull and crudy vapours which environ it, makes it apprehensive, quick, forgetive, full of nimble, fiery, and delectable shapes, which delivered o'er to the voice, the tongue, which is the birth, becomes excellent wit.
The science underlying this rhapsody will not bear much inspection, but it's worth noting all the same the subtlety and attractiveness of the language that Falstaff uses to evoke that first stage of intoxication, when one is elevated without being befuddled.
The second benefit of sherry is the bodily reinforcement it supplies:
The second property of your excellent sherris is the warming of the blood, which before, cold and settled, left the liver white and pale, which is the badge of pusillanimity and cowardice; but the sherris warms it, and makes it course from the inwards to the parts' extremes.
The moralised physiology of the sherry-drinker then gives out visible signs of the encouragement it has received. The devotee of sack is transformed by its action from a pusillanimous coward to a veritable Mars:
It illumineth the face, which, as a beacon, gives warning to all the rest of this little kingdom, man, to arm; and then the vital commoners, and inland petty spirits, muster me all to their captain, the heart; who, great and puffed up with this retinue, doth any deed of courage; and this valour comes of sherris.
Finally, these thoughts lead Falstaff back to Prince Hal, who unlike his abstinent brother has wisely and prudently taken advantage of the health benefits of sherry:
Hereof comes it that Prince Harry is valiant; for the cold blood he did naturally inherit of his father he hath like lean, sterile, and bare land manured, husbanded, and tilled, with excellent endeavour of drinking good and good store of fertile sherris, that he is become very hot and valiant.
