Final answer:
The word 'the' is an article, 'you' is a pronoun, and 'healthily' and 'calmly' are adverbs.
Step-by-step explanation:
The word 'the' is an article, which is a type of adjective that introduces a noun or noun phrase and specifies its definiteness. The word 'you' is a pronoun, which is used to replace a noun or noun phrase to avoid repetition. In the sentence 'Hearken! and observe how healthily --how calmly I can tell the whole story.', 'healthily' and 'calmly' are adverbs that modify the verbs 'tell' and 'observe', respectively.
In the sentence 'It is impossible to say how first the idea entered my brain; but once conceived, it haunted me day and night.', 'impossible' is an adjective that describes the noun 'it', 'first' is an adjective that describes the noun 'idea', and 'my' is a possessive pronoun that shows ownership.
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