The third line turns to the hunt for its image. Legge gives one following the deer without the guidance of the forester, and finding himself only in the midst of the forest, a picture of pursuit undertaken without the proper knowledge needed to succeed at it. The deer, ordinarily tracked with a forester's help, becomes instead the occasion for the hunter to lose himself entirely, deeper in unfamiliar ground with nothing gained for the effort spent.
The line occupies the topmost place of the lower trigram Zhen, the last position before the hexagram crosses into its upper half, and Chinese commentary consistently treats such hinge lines as exposed, belonging fully to neither the trigram beneath nor the one above. Pursuing the deer at this threshold without a guide answers exactly that exposure: ambition reaching for a goal not yet within proper means to attain, at a position already unstable in its own right, compounds one difficulty with another rather than resolving either.
Commentary tradition reads the line as counsel to let go of a pursuit that lacks the guidance it requires rather than to press on regardless. The forester here stands for whatever proper preparation, help, or authority a task actually needs; without it, continued pursuit does not merely fail to catch the deer, it actively deepens the difficulty the hexagram as a whole is built from. Restraint, not further effort, is the line's implicit counsel.