нечего vs. ничего

Question

Up until I started reading through Russian Review Grammar by Marianna Bogojavlensky I had only seen ничего offered as a translation for the English "nothing." Bogojavlensky's text, however, often uses нечего in its example dialogues as in the following sentence:

Если это так, то я могу чувствовать только жалость к тебе, и мне нечего больше прибавить к тому, что я сказал.

Here is the translation the text offers of this sentence: 'If this is so, I can feel only pity for you, and I have nothing to add to what I have said.'

Is the use of нечего in this sentence just a simpler way of saying "у меня нет ничего больше прибавить... ?" One thread I looked at on Word Reference said that ничего stresses a kind of "absolute negative" while нечего merely stresses absence. Can this distinction explain the example given above? Yandex's dictionary defines нечего as 'there is nothing to + inf' or as 'it's no good to + inf.' While I can understand how these definitions differentiate the usage of нечего from the usage of ничего I don't see how this makes "и мне нечего больше прибавить..." preferable to "у меня нет ничего больше прибавить... ?

Answer 1

Ничего along with a verb requires double negation, so it's always about negating actions. But нечего is used with a positive form of the verb, and it denotes a non-existence of an object suitable for action.

So

Я ничего не скажу --> I say nothing; I won't say anything
Мне нечего сказать --> I have nothing to say; There's nothing to say

Я ничего не прибавлю --> I won't add anything
Мне нечего прибавить --> I have nothing to add

On the matter of "у меня нет ничего больше добавить..." - it's really ugly, no native speaker says so.

Answer 2

I think the difference is somewhat akin to "there's nothing" vs. "there isn't anything". For example:

I'll tell you nothing.

Я тебе ничего не скажу.

versus

I can't tell you anything.

Мне нечего тебе сказать.