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Google is hosting its annual shareholders meeting on Wednesday morning. In advance of that gathering, co-founder Sergey Brin released a short letter, in an SEC filing, defending some of the audacious, expensive projects he oversees.

His argument is that shareholders consider Google as a research and development company, not merely a search engine or an ad seller.

“We shared a profound belief in the power of technology to make life better for people everywhere and imagined what life could be like 10, 15, 20 years down the road,” Brin wrote. “Nevertheless, now that we are here, I am amazed at the progress and opportunities. For example, I could not have imagined we would be making a computer that fits in a contact lens, with the potential to make life better for millions of people with diabetes.

“Yet, this is something we are working on today.”

He is referencing the Google X smart contact lens initiative, which recently partnered with pharmaceutical giant Novartis. Omid Kordestani, Google’s business boss, also cited this project onstage at the Code Conference as an example of potential revenue models for the moonshot projects.

In his note, Brin mentioned the self-driving car, too. Google’s homemade vehicles are set to hit the road this summer. The autonomous driving project has felt heat from consumer advocates for its accident reports and from investors for its financial worth. “This project,” Brin wrote, “and others like it are very challenging, and the outcomes are far from certain.”