this beauty should not be seen

[keannu]

Does this "should" mean presumption or obligation? If it is obligation, it sounds awkward as he can show it to others, I think it's presumption, but I'm not sure.

“Under the microscope, I found that snowflakes are miracles of beauty, and I felt sad that this beauty should not be seen and appreciated by others. Every crystal is a masterpiece of design, and no one design is ever repeated. After a snowflake melts, that design is forever lost. Its beauty disappeared, leaving no record behind. I became full of a great desire to show people this wonderful loveliness, ambition to preserve it.” -Wilson Bentley

[J&K Tutoring]

Presumption