Gabriel García Márquez explains (in The Art of Fiction No. 69, The Paris Review) why the butterflies are yellow (or the curtain blue):
You describe seemingly fantastic events in such minute detail that it gives them their own reality. Is this something you have picked up from journalism?
That’s a journalistic trick which you can also apply to literature. For example, if you say that there are elephants flying in the sky, people are not going to believe you. But if you say that there are four hundred and twenty-five elephants flying in the sky, people will probably believe you. One Hundred Years of Solitude is full of that sort of thing. That’s exactly the technique my grandmother used. I remember particularly the story about the character who is surrounded by yellow butterflies. When I was very small there was an electrician who came to the house. I became very curious because he carried a belt with which he used to suspend himself from the electrical posts. My grandmother used to say that every time this man came around, he would leave the house full of butterflies. But when I was writing this, I discovered that if I didn’t say the butterflies were yellow, people would not believe it.
That is the hallmark of a great writer. Also the reason why good story-telling is so damn hard. (Complete interview here: http://www.theparisreview.org/interviews/3196/the-art-of-fiction-no-69-gabriel-garcia-marquez)
As an aside, years ago while reading ‘Life of Pi’, I came to the part where the family plans to migrate, and the mother thinks of all that she'll miss about her life in Pondicherry. Like all good writers to make the part believable Yann Martel names names– for example, the television, she’ll miss watching her favourite shows on, is an Onida, a brand well-recognized by Indians of a certain age because of its standout (though not necessarily good) advertisements that featured a green Devil like figure with the tagline ‘neighbour’s envy, owners pride’. But the novel is set in the summer of 1977. Onida TV began production in 1982. A novel whose premise is believability, is using specific details to make the story believable, but because of such seemingly minor inconsistencies suddenly became hard to believe. Suffice to say I couldn’t complete the book. (Also Doordarshan, the government run sole TV channel in India, didn’t begin national programming until 1982 (the year colour TV was introduced). In 1975 it broadcasted to only 7 Indian cities.)
“…the slovenliness of our language makes it easier for us to have foolish thoughts.”
– George Orwell, Politics and the English Language (1946)Orwell’s words hold true for all forms of communication in any language. Consider the election rhetoric in India. That's why one is grateful that there are people around who pay attention to not just what is said, but also the words used, the context and the tone. And insist that other people do so too.