A necessary or principal cause will be helped and complemented by other causes (predisposing, enabling, precipitating, reinforcing causes) making it sufficient to initiate the disease. Unless a necessary cause has enough support by other causes by means of their complementing and synergistic action, that cause can never become sufficient enough for disease initiation.

These causal partners will not loose their identity and individuality while complementing necessary cause but just help the necessary cause. While doing so, these causal partners form a web of cumulative and synergistic action with the necessary cause to initiate the disease.

That means when a necessary cause is fully complemented with its causal partners, it becomes sufficient enough to cause the disease.