Following the guidance of Jules Chauvet, a biochemist and Beaujolais negociant who is credited as being the godfather of the natural wine movement, the “microscope group” sought to produce wines that displayed purity and honesty - the truth of the vineyard. In pursuit of this, they relied on native yeasts, minimal to no sulphur, working naturally in the vineyards, cool fermentations, restricting yields and picking late to ensure ripe fruit.
It's impossible to overemphasize how radical an idea this was in Beaujolais at the time. The norms of the region included manufactured yeasts with particular aroma signatures (bananas anyone?), pesticides, over-cropping, and chaptalization (adding sugar). These trends occurred as the region’s growers began to modernize and move away from the polyculture, instead relying on grape-growing exclusively for cash. Chauvet, who began making sulphur-free, spontaneously fermented wines in 1951, was in part trying to make wines in the non-interventionalist, old fashioned way with the aid of science. The goal was to produce the most natural, purely expressive wines possible and use science to help solve the problems and reduce the risk.
As such, Metras, Lapierre and the others in the group purchased the same device to observe their wines: the microscope. (Sulphur acts as an antiseptic amongst other things, so curtailing its use carries with it an increased risk that things can go awry in the cellar. They would meet to discuss winemaking and, of course, pull a few corks. "La group a microscope" was how the members referred to themselves.
Kermit Lynch, in his Adventures on the Wine Route, begins the chapter on Beaujolais (where Chauvet is a central figure) with the following: Beaujolais “serves to remind us of the first time that man tasted fermented grape juice and decided that it was an accident worth pursuing.” The work of Metras and the other members can be seen as a combination of two things that Lynch’s quote implies: one, to follow scientifically informed natural methods to express the absolute purity of the Gamay grape; two, to render a wine that is so lively and delicious that each sip fills you with uncomplicated joy.