 By 1920, Russell proposed even greater ontological economy by giving up mental acts and the experiencing subject as distinct from sense data. This meant that the “data” were no longer given to a distinct subject and so were improperly named as “sense data”; henceforth, he spoke of “momentary particulars” or “events”. He explicated this “neutral monism” in the Analysis of Mind (1921: ch. 1). He saw himself as adopting James’s (1904) position, according to which both the self and the external world are composed of one neutral stuff—momentary particulars, characterized by perceptual qualities such as color and shape (for visual particulars). Accordingly, he discarded the act-object analysis of mind and sense perception, as there is no longer recognition of a mind that acts but only of various sequences of momentary particulars. The sequence that includes all the experiences that I’ve had today (and before) constitutes my mind, another sequence of such particulars constitutes your mind. Physical objects, such as a table, become a different sequence of particulars, which are like sensibilia in giving perspectives on a table or a room that is composed of them. If no one’s sequence of particulars intersects with those of a particular classroom, then that room and its contents consist of a series of momentary particulars now occurring without anyone present. The material entities of physics are, as before, treated as constructions from momentary  particulars.[15]