A sea of Panama hats swept over the epochal Pitti Uomo exhibition this year. Classic men and fashion lovers alike topped their heads to shade themselves from the heat and to boost their personal flair. The hat was probably invented to guard people against extreme sun and heavy rain--and for occupational reasons (think hard hats). Later, ceremonial pomp and religious and military circumstances used hats to show status and to make a statement. Now hats just look cool, and even if