Psychologie vom empirischen Standpunkte

Psychologie vom empirischen Standpunkte (1874), by Franz Brentano, is a foundational work in act psychology. Brentano proposed that mental acts are characterized by "intentionality," meaning they are always directed toward an object. This "direction of the mind to an object" is a core concept, distinguishing mental phenomena from physical ones.12

Brentano's work suggests that the mind engages with objects through perception, judgment, and feelings. He argued that intentionality is a defining characteristic of all mental states, a concept sometimes expressed as "consciousness is always consciousness of something". This idea has been highly influential, forming the basis for the work of his students, including Sigmund Freud and Edmund Husserl.21