Although the preschool used the workshop as a shed, they managed to keep it in remarkably good shape.
All the original features in the workshop allowed Garrison and others to make inferences about those who worked there.
Records show the workshop belonged to a master carpenter named Luther Sampson. In the 18th century, master carpenters oversaw entire projects, according to Garrison.
Garrison invited prominent friends and colleagues in the material culture field to come observe the building and piece together the historical significance.
"This is arguably one of the most important historical finds of my lifetime," said Garrison. "The important question is, ‘How do we become historical stewards of the past?'"
Garrison explained how the workbenches inside the joiner's shop displayed clues suggesting how the workers used them.
For instance, some benches were almost sawed to fragments while another was covered in paint, suggesting where different aspects of a woodworking project took place within the shop.
Garrison also found the evidence of a removed fireplace very telling.
"The fireplace told me that they were doing things that required warmth, such as using glue," said Garrison after explaining that 18th century glue could not be used unless it reached a certain temperature.
In addition to offering information about the nature of 18th century woodworking, the building also provided clues about the local ecology and raw materials over 200 years ago.
Garrison's current friend and former colleague, Bill Flynt, used a process called dendrochronology to identify the wood in the joiner's shop as second or third generation wood, meaning New Englanders had already used and replanted copious amounts of trees by that time.
While experts suggested the building could become a National Historic Landmark, Garrison said the push for preservation must come from the local community.
"You have to think about what works best for the school and the town of Duxbury," he said. "Preservation is never as simple as it looks."
As for Garrison, he will always preserve the memory of this rare find.
"It is so important and so interesting. It has been a real treat," he said.