Symbolic reference has its vital
importance, because «what we want to know
about... chiefly resides in those aspects of the world disclosed in causal efficacy:... what we can distinctly register is chiefly to be found among the percepta in the mode of presentational immediacy» (PR 169).
Still has referred to this linear force, which assumes increasing
importance in later paintings, as a «life - line,» the only
symbolic reference he will volunteer
about his work.