I often hear people complain about English classes in schools. The complaints themselves vary, but I will attempt to explain to some of the more common ones. My method in doing this is not conventional - to my knowledge these are not the standard defenses of English class, and my intention is not to give those.
I will attempt to show here that learning a word is worthwhile even when there is no immediate practical use for the word or when a similar, more common word exists.
First, I will define connotation. Two words that are synonymous, for example "precious" and "agreeable", may be differentiated by connotation. Although both are synonyms of "good", they are used in very different situations because they have different implied meanings. These implied meanings are connotations. But on a more subtle level, "exemplary" and "magnanimous" are also separated by connotation. As proficiency with language increases, one word will just "feel" more right than the other for different purposes.
I propose that no two words mean the same thing exactly. Even if they share a definition and perhaps connotations, they will sound different and fit into different cadences. If they did not, then they would truly be the same word already.
Now I will consider thought. People tend to think in their native language, or at least a language they are fluent in. I will assume here at least a weak form of the Sapir-Whorf hypothesis, which is that people with words for something work with that thing more quickly and efficiently. This has been demonstrated with words for color across cultures and in experiments with independently-developed sign languages with words for position. From my limited knowledge, it may be related to the phenomenon of "clumping" in short term-memory.
Now my argument should be easier to make: by learning a word, even if it means the same thing as a word you already know, you increase your vocabulary, however slightly. An increased vocabulary however isn't only desirable for its own sake, but because it aids in the accuracy and speed of thought associated with those concepts.
I hear this complaint often when analyzing poetry and literature, and the teacher proposes a complicated interpretation of a simple gesture. I will not show here that the author did or did not intend that interpretation, but will instead show why I think it is important to explore such unlikely interpretations, apart from the fact that the author may in fact have intended them.
I will admit that this apology is perhaps less persuasive than the last, because here I must explain a personal veiw I hold: I think that humans tend to see the world in patterns. Whether because the universe is particularly elegant, or because a fluke of human perception and cognizance imposes itself on the universe, human experience is filled with parallels, patterns, allegories, analogues, structure and symbolism. I have no evidence for this, nobody outside of myself has ever confirmed this observation, and I know of no formal work that mentions it, but I feel it strongly.
But assume that worldview for a minute. Now look at a bizarre interpretation of an innocuous line of poetry, and consider the author's thoughts as he wrote that line. Perhaps they did not encompass a modern interpretation. But to me, that we can make such an interpreation speaks more to the author's artistry than if it were necessary to understand the author's context entirely before interpreting any of his work: the author could, if only subconsciously, write with enough experience that the patterns of the world are reproduced in his writing.
The argument does not end there though. While the argument is to me a beautiful thing, I do not think that it will justify wild interpretations in the eyes of others. Instead, let me return this interpretation to a large scale: if the patterns of the world are condensed into a piece of literature or poetry, by exploring them there, aren't we practising exploring them in the world? Admittedly, the world is more important, but it's much more dilute; interpreting literature and poetry is important because it's practice for observing the world.