The Tablet to Dr. Forel is a letter of `Abdu'l-Bahá, written on 21 September 1921 in reply to questions asked by Auguste-Henri Forel, a Swiss myrmecologist, neuroanatomist and psychiatrist.
In this tablet `Abdu'l-Bahá discusses the differences between the mineral, vegetable, animal and human worlds, the spiritual nature of man and proofs of the existence of God.
References
Tablet to Dr. Forel Wikipedia(Text) CC BY-SA