 During this development, Russell retained and clarified his conception of occurrent sense data, including the eight points of the Classical Notion. He retained the distinction between mental act and non-mental object (1914a: 76; 1914b: 113). Sense data are non-mental, but they exist as sense data only while they are present to the mind (1914a: 64; 1914b: 110). He now identified two additional entities, inferred rather than constructed, that would figure into his account of the external world: other people’s sense data, inferred from their testimony and ultimately relying on analogy with one’s own mind to posit other minds; and