Ernst Haeckel examining a garnet in its matrix beside a microscope and natural specimens.

Where Haeckel drew the boundary of life

Ernst Haeckel (1834–1919) was a German zoologist. In the preface to Kristallseelen he recalls an observation that unsettled his sense of the boundary between the animate and the inanimate. The physicist Otto Lehmann had studied crystals that display internal order even in a fluid state. Haeckel wanted to know what such a discovery might mean for the concept of life.[1]

From the microscope to a view of nature

Haeckel places Lehmann’s work alongside quite different investigations, including experiments on the sensitivity of plants. A philosophical conviction brings them together for him. He seeks a law of nature that holds for a crystal as readily as for a cell. In the preface a single sentence sums up his position.[1]

All substance possesses life, inorganic as well as organic; all things are animate, crystals as much as organisms.[1]

What a crystal soul means to Haeckel

Haeckel calls his conviction that all of nature belongs to one connected order monism. By speaking of a soul in a crystal he locates even inanimate matter within the same processes from which sensation and life arise. That claim asks much more of the evidence than the observation of liquid crystals itself does. The preface lets us see the precise step at which an observation about the order of matter becomes a philosophical interpretation.[1]