I would like to know what "made notes for a little thesis" means in the following sentences:
Collins made notes for a little thesis pointing out the inferiority of the original mosaics to their photographs. Here was planted the seed of what became his life's harvest. When, many years later, there appreared the first massive volume of his still unfinished work on Byzantine Art, I was touched to find among two pages of polite, preliminary acknowledgements of debt, my own name: "...to Charles Ryder, with the aid of whose all-seeing eyes I first saw the Mausoleum of Galla Placidia and San Vitale..."
This is an excerpt from Brideshead Revisited by Evelyn Waugh. The narrator Charles went on a trip to Ravenna in Italy with his scholarly friend named Collins. Although Charles found the place boring, Collins took this opportunity to prepare for his little thesis.
But I could not grasp what "make notes for" meant in this context, and thus found it difficult to understand what exactly Collins did in the underlined part. Did he just scribbled here and there for his little thesis? Or did he actually make a formal first draft for the thesis?
I would very much appreciate your help.