During the war, he switched to Polish out of solidarity with his homeland after the German invasion,[2] and as a result, his major works in ontology went largely unnoticed and undetected by the wider world and philosophical community.

[6] Ingarden previously suggested that he transfer to Lwów and write a new dissertation under Twardowski due to an increasing tension between Germany and Poland but Husserl refused and was uninterested.

This involved an analysis of Zygmunt Lempicki's "W sprawie uzasadnienia poetyki czystej" (On the Justification of Pure Poetics).

[5] Ingarden became a professor at Nicolaus Copernicus University in Toruń in 1945 shortly after the war but was banned in 1946 under the Communist regime.

That is why[citation needed] Ingarden is one of the most renowned phenomenological ontologists, as he strove to describe the ontological structure and state of being of various objects based on the essential features of any experience that could provide such knowledge.

[8] In this book, Ingarden argued that a literary work of art is a purely intentional object and is a product of the author's conscious acts.

[8] This work would contribute to the development of the literary theory called reader-response criticism and influence scholars such as René Wellek and Wolfgang Iser.

[12] In his stratification of literary work of art, he cited that aesthetic value is the polyphonic harmony that arises between these strata of meaning.

The group, which focused on aesthetics and descriptive psychology, attracted some of Twardowski's students including Leopold Blaustein and Eugénie Ginsberg.