The word which our teacher here translates as ‘duty’ is dharma, which means what-is-to-be-done according-to-tradition. We cannot extract moral principles by reasoning about them, because ultimate goals are indefinite. In his persistent attempts to do this during his long life, Russell changed his position repeatedly. In fact he held, one after another, all the main positions except religious revelation. His last conclusion was, that right action was that which leads to ‘the maximum possible satisfaction of desire’.
Even this was not satisfactory, for he recognized that some desires are ‘higher’ than others. In other words, they may be more desirable, so the reasoning becomes circular. Moore’s Principia Ethica, in its vulgarized form ‘If it feels good, do it’ is popular today; Dr. Shastri said that it was a doctrine of darkness.
The three main pillars of right conduct for a yogin are set out in Ch. XVII of the Gita: Gift, Sacrifice, Austerity.
They are to be practised as ought-to-be-done, not to satisfy a desire, even a compassionate desire. Compassion alone often leads to hatred of a supposed guilty party.
If desire is associated with duty, it is not dharma; it is something from your own mind.
Friends of an collapsing alcoholic may know that his only change is to be refused alcohol; nevertheless when he turns up at the door, pleading, some of them have not the heart to refuse him a drink. They know it is ruining him, but they cannot manage to refuse.
To give when it ought-to-be-given, and not otherwise, is the yogic dharma, and it is effective.