Note particularly Avicenna or Constantinus says in the commencement of his own Antidotarius that the compounding of simples is essential, since for three causes it (a simple) does not suffice for curing every disease. The first cause is on account of the nature of the disease. The second cause is on account of the affected members. The third cause is on account of the nature of the simple. For these reasons the old physicians, when constrained by this necessity, made composite medicines from simples so that they might be able to carry out their intention in every single defect, and to compound with perfection and advantage.