Who left the light in (the branch)?

Someone on a message board has just pointed out, in an example sentence, a difference in meaning between the intransitive る and transitive す verb forms. Recalls a tanzaku (短冊) haiku I've had around the house for years:

一枝に	hito eda ni	in one branch
光のこして	hikari nokoshite	light remains
里の春	sato no haru	spring in the village (back home)

The straightforward reading is that (sun)light just remains, but shifting to transitive—what?—implies a subject, someone who is leaving the light there? Certainly, a new way of looking at the poem.

Proverb:

虎は死して皮を留め
人は死して名を残す

tora ha shishite, kawa o todome;
hito ha shishite, na o nokosu

a tiger dies and leaves its skin;
a person dies and leaves their name (o nokosu)

The person (人) leaves (残す) the object (名を).

を vs が: "結果だけが残る！！！"
—only the results/consequences remain (ga nokoru)!

That light, in that one branch—has someone left it there?