Abstract
The aim of the paper is to elaborate on the metaphysical distinction between ideal signs and physical signs in terms of the method of abstraction. Ideal signs are derived from physical signs by eliminating certain kinds of properties as theoretically superfluous. Ideal signs are claimed to be instructions that prescribe how physical signs are to be produced in their graphic form, acoustic form or any other suitable form. It is examined which level of abstraction is permitted in the case of ideal signs, i.e., which properties can be eliminated while admitting that the resulting abstract object can be still considered a sign. It is argued that one cannot eliminate the properties that are connected with the syntactic and semantic aspects of signs.