Final answer:
The 1923 mystical work written by Kahlil Gibran is 'The Prophet', a collection of poetic essays that delve into themes of life and spirituality.
Step-by-step explanation:
The mystical work written by Kahlil Gibran and published in 1923 is D) The Prophet. This book is a collection of poetic essays that explore life, love, and spirituality, and has been influential across the globe, impacting various facets of culture and philosophy. It is well-known for its beautiful language and profound insights into the human condition.