MR. SHERLOCK HOLMES, who was usually very late in the morning, save upon those not infrequent occasions when he was up all night, was seated at the breakfast table.
This is from novel <SHERLOCK HOLMES>
my question is "save upon those not infrequent occasions" meaning what in the whole sentence.
thank you guys!
The whole sentence implies that there is something suspicious about the fact he is at breakfast, simply because it is so unusual for it to happen.
In this case, "save" means "except" or "only". The only way Mr. Holmes would be up early were on those rare instances when he did not sleep at night.