I am confused as to when to use "a need" and "the need".
I felt a/the need to take a shower.
With this sentence, we are assuming that there was no mention about the need to take shower before.
I do not think it is defined by first mentioned rule. I am assuming that it depends on the speaker.
If the speaker acknowledges that it is a definite need, that of taking a shower, then he will use "the".
If he feels no need to denote its definiteness and acknowledges that it is told for the first time, he will use "a".
Am I right?