Seeking to bridge the gap between sciences and arts, this chapter explores the deeper connections linking together Mathematics and Poetry. From several common areas where they meet each other like old friends to the centrality of metaphor and metaphorical thinking in both domains, Metaphor: a Key Element of Beauty in Poetry and Mathematics endeavors to carve out a dynamic and playful transdisciplinary space in which differences melt into similarities, allowing the mind to expansively perceive and embrace the boundless nature of the interaction between two fields commonly seen as being separate and disjoint.