apprehension, anxious or troubling thought, anxiety

to make a horse gallop

think, reason, consider

cause to run

look all around, scan

keep up active or brisk correspondence, send letters or petitions, etc.

to indulge into something

indulge in speculation, imagine, let thoughts roam

consider, think freely, let mind roam

make (a horse) gallop

to put forth the hand with rapidity, to stretch (at or after), to go beyond bounds, to commit excess, to encroach

exercise one's mind, think

keep up active or brisk correspondence, send letters or petitions, etc.

to imagine, guess, speculate

cheat, fool, spin a yarn

allusion to someone who worries about someone else's troubles