it's hard to explain, even though native speaker. it was about philosophy. Personally I think here "万物一体之仁" means a kind thought to the every thing in the world, and what you “feeling” about them, you feel every thing are equal, even plant and people, then you will respect every thing. while you cant get this "feel", you feel nature to treat thing in different rules, of course I am higher class than "him". This is my personal opinion, not quite exactly so, and I can tell you is you are learning the very deep Chinese Culture.