"Herr Mendel, it is good to see you, to what do I owe this honor?" he said, putting down the cut glass bowl he had been cleaning and turning towards the monk.

"A problem, I'm afraid Herr Rosenstrauch, a problem for which I need your help." Mendel looked around him. He was standing on one side of a long counter that ran the length of the small store. Behind the counter were shelves, and on each shelf were displayed vases, bowls, inkwells, mirrors, jugs and a host of other glass objects. But Mendel had not come to Rosenstrauch's Glassatt to buy a tankard.

He placed the brown paper parcel on the counter. "I dropped my microscope," he said, shaking his head at the memory of his carelessness, "it's broken, and I would like you to see if you can repair it for me."

"Of course," said Herr Rosenstrauch waving his hands and pushing his sleeves further up his arms. "Show me."

Mendel unwrapped the parcel and revealed a sorry sight. His one and only microscope, the instrument that he had used all through his time at the University of Vienna and was now one of his most treasured possessions, lay in pieces on the counter.

"It was a silly accident," Mendel said, poking the pieces with one of his fingers. "I had just received a set of prepared microscope slides from one of my Professors, Herr Docktor Ausbach, who had asked me to help him identify some of the specimens he had been collecting. I was in such a hurry to set up my microscope that I knocked it off my table, onto the floor, and broke it in several pieces."

Rosenstrauch tut-tutted sympathetically. "So you still keep in touch with your old Professors?" he said, picking up a small box of microscope lenses, opening it and examining the contents.

"Yes," replied Mendel, "I correspond with Nageli at the University of Munich, and occasionally Herr Doktor Franz at the Philosophical Institute. But Professor Ausbach is the only one who asks me to help him in his work." He looked at the broken instrument. "Is there anything you can do?"

Rosenstrauch did not answer at once. He was a measured man who had learned the hard way to be careful in all his actions. It had taken him many years to build up his small glass cutting workshop in Brno, from which he now made a modest living, but far too many of those years had been hard and unrewarding. There were still many of the ansehnlich Brno citizens who would not patronize his establishment.

Those that did found that he sold good quality glassware, but few of his patrons knew that as a sideline, Herr Rosenstrauch had a passion for the science of optiks. Whenever he could, he bought himself lenses and prisms with which he carried out experiments on the properties of light. As a profitable side line, he also built high quality telescopes, cameras and other optical instruments such as microscopes. It was because of his interest in physics and the principles of bending light that he had tried, only once, to join the Brno Science Society, but the hostility that greeted his application had convinced him to look else where for intellectual support. That was how he had found Mendel, and a comfortable friendship had sprung up between the two scientists.

"Come with me. Let's see what we can do," the glass maker said, picking up the small box of lenses and leaving the broken microscope to Mendel. Together they moved to the back of the store, through a curtained off doorway and into Rosenstrauch's private workshop.