There are a lot of Alchemy references in this song. An Alchemists main goal was to turn lead into gold and it seems to me the whole song is sort of saying that he's got something that he thinks is good, his mind or his thoughts or beliefs, but "They", that ubiquitous They, don't think its good enough. They're saying, "what you have is lead not gold, its worthless and useless.", but in the chorus the singer is fighting back saying that their gold is fake, "a trick of the night".
There are a lot of Alchemy references in this song. An Alchemists main goal was to turn lead into gold and it seems to me the whole song is sort of saying that he's got something that he thinks is good, his mind or his thoughts or beliefs, but "They", that ubiquitous They, don't think its good enough. They're saying, "what you have is lead not gold, its worthless and useless.", but in the chorus the singer is fighting back saying that their gold is fake, "a trick of the night".