January 16, 1838

Franz Brentano (January 16, 1838 to March 17, 1917) is famous for his contributions to psychology and philosophy, particularly his idea of intentionality, by which Brentano meant to distinguish the phenomena of the external and internal worlds. Psychology from an Empirical Standpoint is the English title his textbook, first published in 1874. From his lectern at the University of Vienna, he taught many notable twentieth century thinkers, such as Husserl and Rudolf Steiner.

In explaining Franz Brentano's contributions to pyschology, Radu J. Bogdan in his book
Our Own Minds: Sociocultural Grounds for Self-Consciousness (2010), proceeds to elucidate the idea of intentionality. We summarize:

Iintentionality was a construct Franz Brentano reintroduced into psychology. It has two aspects, directedness and aboutness, basically according to whether a mental state is engaged with the external world, or the inner. Aboutness is supposed to describe how the mind deals with the external world. Also, Brentano noticed that the mind can itself come up with thoughts or topics, rather than having them presented externally. This is called directness, and Brentano came up with the phrase "intentional non-existence" to connote the mind can up with something NOT related to the external world at all. Imagination might be another word for this. It is possible few have noticed that in fact there is no such talent for the mind as "intentional non-existence." The example used by Bogdan is the mind conjures up 'tallest pink joke.' Now in fact, that produces nothing specific in the mind, just words, no pictures.  But skipping these details let's get to the cat part. The example used to explain aboutness is when you think of a cat, having seen a cat in your range of vision.

Brentano was Husserl's teacher, as well as Freuds, and other 20th century lights.