she'll know "that" refers to.
Line-3Legge: The third line, dynamic, shows us a feudal prince presenting his offerings to the Son of Heaven. An inferior man would be unequal to such a duty.
Wilhelm/Baynes: A prince offers it to the Son of Heaven. A petty man cannot do this.
Blofeld: A prince may win rewards from his emperor, but this is beyond an ordinary man's power.
Liu: A duke makes an offering to the emperor. The inferior man is unable to do this.
Ritsema/Karcher: A prince availing-of Growing, tending- towards heavenly sonhood. Small People nowhere controlling.
Shaughnessy: The duke uses aromatic grass to the Son of Heaven; the little man is not capable of it.
Cleary (1): The work of barons serves the son of heaven. Petty people are incapable of this.
Cleary (2): Impartial action gets through to the ruler. Small people, etc.
Wu: A duke has the honor of dining with the king. The little man is unworthy of the honor.
Line 3 You are in a unique position to help another = no one else can do this. Don’t measure what you give, it will only undermine your success in achieving your aim. The empty vessel of being open is always filled when in the service of others. A sacrifice may be required and another may rely on your support. However, know that sacrificing to others can also lead to their resentment which is not something you can control. There is a fine balance required, so if you open your hand make sure the gesture is with the attitude of abundance and not what you will receive in return.