Final answer:
Joy did not want one of the core memories to be blue because in the movie Inside Out, where this scenario is likely from, blue memories represent sadness. Joy's main goal is to ensure that Riley remains happy, which is why she avoids blue, a color often symbolizing sadness or hardship in various narratives.
Step-by-step explanation:
The excerpts provided hint at themes of identity, color and its symbolic significance, and the internal struggles associated with them. However, Joy's reluctance to have a blue core memory isn't directly linked to the given texts, but rather it seems to be a reference to the 2015 Pixar animated film Inside Out, where Joy, one of the five emotions personified, aspires to keep the core memories of their human host, Riley, happy. In the film, blue memories represent sadness, and Joy's objective is to maintain Riley's optimistic and joyful outlook on life, hence her aversion to blue core memories, which could bring about sadness.
Color symbolism is recurrent in various works of literature and art. The provided quotes from different sources discuss the implications of color and light, ranging from a means of creating a vibrant and noteworthy presence to a metaphor for psychological and social barriers. In these narratives, the color blue often emerges as a symbol of despondency, introspection, or life's hardships, which likely informs Joy's reluctance in the movie context.