The fog too is a symbol of the pervasive contamination that corrupts society: drug addiction (opium was readily available to all); crippling poverty; a hidebound bureaucratic system (epitomised by the Law); the misguided philanthropy of Mrs Jellaby and Mrs Pardiggle, seeking to help those abroad whilst ignoring the poor at home; and one of Dickens???s key themes, small-pox spread through poor sani