{ 1 } - our duty not to harm others.
{ 2 } - the fact that non-maleficence is stronger than beneficence.
{ 3 } - the importance of sometimes just enjoying ourselves instead of always trying to be useful.
{ 4 } - our duty to do good to others.

Ima says that, in general, it's not right to harm one person to help another or promote social usefulness. One of the defects of utilitarianism is that it permits any harm to the individual for the sake of maximizing pleasure.