Doctrine of signatures: (above) a plant with roots resembling the human hand, and (below) a hand. Coloured ink drawing by C. Etheridge, 1906, after G.B. Della Porta.

Previous title, replaced September 2023 : Doctrine of signatures: (above) a plant with roots resembling the human hand, and (below) a hand. Coloured ink drawing, c. 1923, after G.B. Della Porta.

In his Phytognomica, Della Porta discerns the hidden qualities of plants from the analogy of their forms with comparable features of animals. Those features of animals are "signs" which signify the same effects in plants which they have in animals: "ut cui signum competat, eidem et effectus: et cui effectio, pariter & signum: & quae signis vacent, & effectibus vacent" (Phytognomica, lib I, cap. xiii, Rouen 1650, p. 26); in English "That to which a sign belongs, to it also the effect belongs; and that to which the effect belongs, equally to it the sign belongs; and those which lack the signs also lack the effects"

Plant recommended for treating diseases of the finger joints etc.

1906

1 drawing : ink, with watercolour

Doctrine of signatures. Plant resembling a hand. From a woodcut of the XVI. century.

Wellcome Collection 525036i

After: G.B. Della Porta, Phytognomica Io. Baptistæ Neopolitani, octo libris contenta, lib. III, cap. xliii (Rouen 1650 p. 240)