i reviewed for him a brief history of the toxin , how it had been discovered by the ancient phoenicians and brought to egypt , why it was preferred by assassins and certain governments ' secret police ( extremely slow-acting in the proper dosages , giving the perpetrators days to effect their getaway ) , what he might expect in the coming hours-headaches , heart palpitations , shortness of breath , dizziness , nausea , insomnia-the lecture delivered in a dry monotone , like that of a white-coated man to a hall filled with other white-coated men .