Our old friend Nietzsche
Nuts and bolts of existentialism all the way back to the Phenomenology.
Quote
Phenomenology, in Husserl's conception, is primarily concerned with the systematic reflection on and study of the structures of consciousness and the phenomena that appear in acts of consciousness. This ontology (study of reality) can be clearly differentiated from the Cartesian method of analysis which sees the world as objects, sets of objects, and objects acting and reacting upon one another.
The concept of thoughts/ideas being "Intentional Objects".
Nietzsche "The Consequences of Ideas" https://www.youtube.com/watch?v=xWnF8cDlj88 (https://www.youtube.com/watch?v=xWnF8cDlj88)