In the late 1970's Vincent sent Alan a bottle of wine and a book as a gift. In the book Allan found a photo of his friend Vincent, a picture of Arizona with an "X" over the town of Mesa, a picture of a house, and a bingo card with three of the numbers circled.
These items were all part of a treasure map. Allan followed the map to Mesa, Arizona where he searched for the "one tree that became three" from the picture. He found the treasure and brought it back home. Allan then went home with the treasure, bought and installed a safe, and placed the treasure in it.
For reasons unknown Allan left over $50K in the hidden safe, left the combination on a card in the cupboard, and vanished never to be seen or heard from again. 35 years later Allan's stash of money has been rediscovered.
The biggest thing is if Allan abandoned $51K can it be assumed that the treasure Vincent gave him was intently larger than $51K? Perhaps the answer resides in the passage underlined by Vincent, “Most Modern Readers will be reluctant to believe that perfect happiness is attainable by methods of which their modern world knows nothing.” Perhaps Vincent's treasure was something more than money...