Pierre Lecomte du Noüy 1938 Handwritten Letter to Son, & Rhode Island Envelope For Sale

Pierre Lecomte du Noüy - 1938 handwritten personal letter (ALS) from the famous French biophysicist and author of Human Destiny to his son Philippe ("Billy"). Signed "Dad" - includes the original 1938 postal envelope.
Overview:
Up for sale is a deeply personal piece of scientific and philosophical history: a 100% authentic, 2-page entirely handwritten letter by the renowned French biophysicist and author Pierre Lecomte du Noüy (1883–1947). Written in 1938 from Rhode Island, the letter is addressed to his son, Philippe Lecomte du Noüy (affectionately called "Billy"), who was living in Surrey, England at the time.Significance & Context:
Pierre Lecomte du Noüy is celebrated globally for his groundbreaking work on surface tension at the Rockefeller Institute and his highly influential philosophical books, including Biological Time (1937) and Human Destiny (1947).This letter provides an intimate look into his private life during a highly productive era of his career. Because the letter was sent to his son, it is affectionately signed "Dad" rather than with his formal full name.Provenance & Postal History:
The letter is accompanied by its original, intact trans-Atlantic postal envelope. The envelope provides ironclad provenance and context for the letter:

• Origin Postmark: Rhode Island, 1938
• Destination Address: Surrey, England

Condition Report:

• Letter: Excellent vintage condition. Bold, highly legible ink handwriting. 
• Envelope: Complete and intact with minimal edge wear from international transit. Period-accurate U.S. postage stamps and clear, legible postmark strikes.

Please review  photos to evaluate the condition and handwriting details before purchasing.