Factor in the relative obscurity of Rizal's annotations to Morga:
; Censorship during the Spanish colonial period
; the Rizal edition of Morga was banned in the Philippines
; copies confiscated by Spanish customs in Manila
;other ports of entry were destroyed due to the burning of one particularly large shipment of the Morga
; the book attained "rare" and "out of print status within a year of its publication.
; It did not have a second printing
; few copies in circulation were left hidden and unread by frightened owners