Full Idea
Mendeleev rejected one unifying principles in favour of three basic components of nature: matter (substance), force (energy), and spirit (soul). 'Spirit' is said to be what we now mean by essentialism - what is irreducibly peculiar to the object.
Gist of Idea
Mendeleev saw three principles in nature: matter, force and spirit (where the latter seems to be essence)
Source
report of Dmitri Mendeleev (The Principles of Chemistry [1870]) by Eric R. Scerri - The Periodic Table 04 'Making'
Book Reference
Scerri,Eric R.: 'The Periodic Table' [OUP 2007], p.118
Related Ideas
Idea 17400 Mendeleev focused on abstract elements, not simple substances, so he got to their essence [Mendeleev, by Scerri]
Idea 17411 If all elements are multiples of one (of hydrogen), that suggests once again that matter is unified [Scerri]