The toughest thing in hitting shouldn't be deciding when to swing. It is, for me, deciding when not to swing. You should be swinging from the time you get into the batter's box until something says don't swing.
A man in love will jump to pick up a glove or a bouquet for a silly girl of sixteen, whilst at home he will permit his aged mother to carry pails of water and armfuls of wood, or his wife to lug a twenty-pound baby, hour after hour, without ever offe