For the Platonic realist, the essences of things are transcendent, existing in a “third realm” beyond both the material world and any mind. For the Aristotelian realist, essences are immanent, existing as constituents of the things themselves. For instance, the Form of Tree, for Plato, exists utterly apart from any particular tree, while for Aristotle a tree’s form (no caps needed, thank you very much) is a metaphysical component of the tree itself, not something external to it. Where they agree is in holding that the form or essence of the tree is something objective and repeatable, that this tree, that tree, and the other tree share the same nature, and that that nature determines what is good for trees as a matter of objective fact – such as that a tree that sinks its roots deep into the soil so as to give it stability and take in nutrients is to that extent a good tree, and that a tree which due to genetic defect or injury is unable to sink its roots very deep is to that extent bad and defective qua tree.