   We have seen how Leśniewski developed his logical systems in the struggle to provide an antinomy-free foundation for mathematics, comparable to those of Frege or Whitehead and Russell, but without their defects. His gradual move from a highly stylized prose-with-variables to fully formalized systems precluded him from considering his logic as an uninterpreted system, as did Hilbert. From the start, he considered his systems, even the fully formalized ones, to be comprised of constant expressions, primitive and defined, with a fixed intended meaning, which he attempted to make clear by examples and elucidations. He also considered all his axioms and theorems to be true. In this he was following Frege and Russell, who likewise did not envisage an external source as somehow conveying a meaning upon expressions and truth upon sentences of logic.