Undeniably, many quotations can be found to support such a view. Opposite interpretations, emphasizing the exclusive role of the environment, have focused on other passages of the naturalist's works. In both cases, exegetes have often resorted to the dubious method of isolating the passages that bear out their view from the general context of Lamarck's thought and from the problems he faced in developing the successive versions of his ideas. It is this lack of clarity that makes Lamarck difficult to read and interpret. Lamarckian doctrines can be summarized in six points.
Organic entities are the products of nature, and the production takes places through eons of time.
Only the simplest bodies are fashioned immediately. The environment in which an organism originates causes the gradual development of organs. This is the cause of diversity. Growth is inherent in all parts of the organism. Changes in conditions cause the modification of the organism over time.