It should also be born in mind that the research on 'movement' and the dynamic outlook on the world, which were the basis of Futurist theory, in no way required one to paint nothing but speeding cars or ballerinas in action; for a person who is seated, or an inanimate object, though apparently static, could be considered dynamically and suggest dynamic forms. I may mention as an example [his paintings] the 'Portrait of Madame S.' (1912) and the 'Seated Woman' (1914).

p. 248 - after 1960, and posthumous - 'Letters of the great artists', 1963