"Celtic Worlds", the first volume of "Autumnal Rites", is an encyclopedic journey into ancient and early medieval Celtic religion, history, and folklore. The book is a unique collection of haiku poetry inspired by typical autumnal atmosphere of incessant rain, bone-chilling wind, and dense fog, as well as pale sunlight and forests dressed in fire and gold. "Celtic Worlds" also includes comprehensive commentaries, which aim to explain the meaning and significance of traditions, customs, deities, and historical events depicted in the poems. The book is a mythical peregrination across ancient Celtic lands. It begins in the lush forests and the fertile plains of Gaul. Then, it leads through the tin mines of Cornwall and the rugged hills of Wales and northern Britain. The journey continues through the lochs and mountains of Scotland, to finally end at the western shore of Ireland.