a peaceful and happy period (always in the phrase "halcyon days")
My undergraduate years were the halcyon days of my life, when I had nothing to worry about but the deep mysteries of philosophy and love.
halkyon (kingfisher) (Greek)
halycon can be considered as opposite of cyclone. just imagine a cyclone. you will understand what I mean HALcyOn = HAL can represent a HALO, which is symbolic of peace and harmony