Noah’s Ark is the “big ship” used by God in the Bible to save mankind and the species. Later generations naturally used it as a metaphor for the "salvation" boat. The Garden of Eden is the place where God created humans in the Bible. It represents the ultimate in purity, beauty and goodwill. In a theological context, it is understandable that Westerners are accustomed to using these two things as symbols of salvation and beauty.