I have been wondering in my head when is it more appropriate grammatically and more appropriate in terms of the English language to use word selfsame instead of same.
The research that I have done suggests that 'same' can be used as an adjective and a pronoun and as an adverb. While selfsame can only be used as an adjective. So comparably it would appear to be only a subset of grammatical cases where its used. That being said, I am having still having trouble imagining a sentence or a set of rules to follow that indicate when you should use selfsame instead of same.
Google define gives this example:
He was standing in the selfsame spot you're filling now.
But I can easily see 'same' replacing 'selfsame' without an apparent change in meaning of the sentence.