From the standpoint of exact natural science, of the explanation of nature from causes, the assumption of an earth-soul is... an hypothesis for the e… - Bernhard Riemann

There remains only the assumption that the ponderable masses within the rigid earth-crust are supporters of the soul-life of the earth.

The word hypothesis has now a somewhat different significance from that given it by Newton. We are now accustomed to understand by hypothesis all thoughts connected with the phenomena.
Newton was far from the crude thought that explanation of phenomena could be attained by abstraction.

The different thought-processes seem to differ chiefly in respect to their temporal rhythm. If plants have souls, then hours and days must be for them what seconds are for us. The corresponding period for the earth-soul, at least for its outward activity, possibly embraces many thousands of years.