Student or Learner
as in here:
"By which one sees how inconsiderate those persons are, who, from the absence of its officious manifestations in the world, complain that there is not much gratitude extant; when the truth is, that there is as much of it as there is of modesty; but, both being for the most part votarists of the shade, for the most part keep out of sight."?
You can't start a sentence with 'by which', you immediately wonder 'By what?'