apse of time.

HP: Does &quot;line&quot; refer to the trajectory of particle?  In which case the line
    may be defined by the particle but it is created by forces (other particles)
    and therefore line, particle, and forces are inextricably related. 

HP: In this comparison, he appears to mean that the sign corresponds to the line
    and human thought to the particle.  If so, then could he mean that human thought
    and external forces (experience, environment) create or define the sign?  That is
    