''Ones ideas must be broad as nature if they are to interpret nature.'' is a quote by Arthur Conan Doyle used in his most important work ''Sherlock Holmes'' where the Sherlock is talking about this quote.
Since the nature is the widest thing in the world, people should have ideas wide as it so they can find out the idea that they are tending to. Since the Sherlock Holmes is individual detective who is researching and exploring situations, he is considering that he must have knowledge about every little thing that idea he is trying to explore.
