In 1859–1860, Johan Jacob Borelius published two diatribes against Christopher Jacob Boström, the then dominating philosopher in Sweden. Boström was accused of inconsistency, because he asserted the principle of esse est percipi while at the same time maintaining that different agents can perceive one and the same thing differently. It is suggested that Borelius misunderstood Boström’s intention. In his printed defence, in 1860, Boström clarifies his use of a dual conception of meaning, resembling Frege’s distinction between Sinn (sense) and Bedeutung (reference) some thirty years later. Boström appears to equate the reference of esse with that of percipi, whereas Borelius argued as if the principle concerned the senses of the two expressions. According to Borelius, two observers cannot possibly have different perceptions of the same object, if “to be” means “to be perceived”. In Boström’s view, as reconstructed here, two different phenomenal perceptions may well refer to one and the same true object, of which the phenomena are aspects. The true object exists in virtue of its being determined by God’s perfect ideas.