138 Wisconsin Academy of Sciences, Arts and Letters. 
forerunner of the unfolded trio, let that protean forerunner be 
expressed by P. Let also the relation between forerunner and 
unfolded trio be whatever you please, expressed by “precedes.” 
Again let “passenger,” “strike” and “freight” be accepted as 
representing any three ideas which can together constitute a 
lateral thought. Finally, let “I saw” be regarded as express¬ 
ing any two ideas which together with P can form a central 
thought. 
Accordingly, the amended diagram 
f passenger “ 
(I saw [P.) precedes strike 
which now may be regarded as of universal application. 
Under the hint which it offers, I pass now in review the 
mental operation which it aims to indicate, and seem to find 
that as cerebration continues, after reaching in the expres- 
sional act what is indicated by P, its further stages are dis¬ 
tinctly lateral to the preceding (see page 136). Indeed, I find, 
in all, three stages—or grades of thought-perspective: a central, 
of which the end is marked by P; a lateral, which lies abreast 
of “P precedes strike”; and a sublateral, which coincides with 
“passenger strike freight.” In short, abstracting from the 
single out jutting but not detached idea expressed by “strike,” 
I find that the unfolded trio of thought is two removes from 
being central. 
I have not yet however completely established my proposi¬ 
tion; for it is possible to conceive a mental operation partly 
the reverse of that above described, but virtually equivalent, 
and therefore to be reckoned with. To indicate this operation, 
I reverse my diagram, continuing all my symbols in their foi- 
mer universal value, but somewhat more conspicuously using 
distance from left to right, to indicate the passage of time. 
Accordingly the diagram 
(a) I saw. 
passenger p 
(b) strike .is followed by. 
freight 
