I think what it means is that the more you know, the more you realize the less you know. Even and especially for scientists, the mysteries of life become more grand and awe-inspiring. I'm thinking about Neil deGrasse Tyson, Stephen Hawking, et al.

You'd really need to see the context in which he made the statement.

Remember that it was Pasteur who demonstrated the falsity of the Spontaneous Generation doctrine which claimed that life could spring forth anywhere; an old shirt and grain could create mice. The belief in spontaneous generation was endorsed by the church, and the development of life was considered to be magical. Thus, disproving spontaneous generation was problematic. Rigorously demonstrating that life only came from other life was a huge game changer in understanding what life was. Creating a vaccine that prevented chicken cholera presented a mechanical explanation of disease. Again, this was at odds with religious doctrine that claimed, (and still claims,) that illness is an expression of God's will. Pasteur was definitely encroaching on the Church's territory, and for the Christians of his day, they surely weren't too happy to have their established understanding of reality upended.

What he is trying to tell us is that he has no clue what science means.

That's a remark from the very beginning of the Scientific Age, when people were wowed by the "little beasties" they could suddenly see under that fantastic invention, the microscope. Get over it, he did !