Indeed, the phrase "sich einfühlen" was used by Herder in the 18th century. Nonetheless, Robert Vischer's exploration was the first significant discussion of the concept of Einfühlung under that precise name.
In fact, the phrase "sich einfühlen" was utilized by Herder in the 18th century. However, Robert Vischer's study represented the first major discussion of the concept of Einfühlung under its precise title.