In the period of invasion, the doctor must hold his breath, for 'the beginnings of disease reveal its class, its genus, and its species'; when the symptoms increase and become more marked, it is enough 'to diminish their violence and reduce the pains'; when the disease has settled in, one must 'follow step by step the paths followed by nature', strengthening it if it is too weak, diminishing it if it strives too vigorously to destroy what resists it'.'