What is ethics?

Here's a provision of examination questions set by Hitotsubashi Univ. in 2006.

It is the sum total of those things that an individual imposes on himself or denies himself, not primarily to further his own welfare or happiness - that would be nothing more than egotism  - but in consideration of the interests or the rights of others, in order to stay true to a certain conception of humanity and of himself.

It is the sum of my duties, in other words of the imperatives which I believe to be legitimate - even if from time to time, as everyone does, I break them.

It is the law which I impose - which I should impose - upon myself; indepedently of the judgement of others and of any expectation of reward or sanction.

"What should I do?" and not: "What should others do?" This is what distinguishes ethics from moralizing.