Why doesn't Dr Mortimer want Sherlock to go?

Dr. Mortimer is concerned about Sherlock Holmes's safety and well-being, as he believes that the investigation into the mysterious events surrounding the Baskerville estate poses significant danger. He fears that Holmes's pursuit of the truth might lead him into perilous situations, especially given the legend of the supernatural hound. Mortimer's reluctance reflects his protective instincts toward Holmes and his awareness of the chilling local lore surrounding the Baskerville family.