Note82 that there is an external cause ... the fault of a humour or humours, because of their quantity; the letting of a vein avails there. In one kind there is the fault of a humour on account of causon or putrid substance or quality wherein drawing avails; and in another kind it is the fault of humours, as regards their83 own sharpness and vehemence; wherein a change avails. Therefore there is the fault of a humour in every disease, nevertheless it is not material, that is it has no matter in it, which is subservient to, or necessary for, evacuation.