The point of departure is the paradoxical finding that Spinoza is sometimes presented as the a-historical philosopher par excellence, while his Theological-Political Treatise is truly an historian’s work. The paper develops the hypothesis that historiography, as Spinoza himself practices, is a task of political ethics, analogous to the one to be found in the first section of the fifth part of the Ethics. Against interpretations developed by Vittorio Morfino, drawing on Althusser, historical knowledge is not a knowledge of the third kind but of the second kind.