John Locke and his works - particularly An Essay Concerning Human Understanding - are regularly and rightly presented as foundations for the Age of Enlightenment. His primary epistemological message - that the mind at birth is a blank sheet waiting to be filled by the experiences of the senses - complemented his primary political message: that human beings are free and equal and have the right to envision, create and direct the governments that rule them and the societies within which they live.

Being and Time was published in 1927 during the Weimar period in Germany, a time of political, social and economic turmoil. Heidegger himself did not escape the pressures and his nationalism, and undeniable anti-Semitism in the following decades cast a shadow over the man, but not the work. Being and Time is not coloured by expressions of his later views (unlike other writings) and remains an outstanding document.

Aristotle’s Organon comprises six key essays on logic, initially collected by Theophrastus, his successor as head of the Peripatetic school, and given its final form by Andronicus some three centuries later. The six essays are: Categories, On Interpretation, Prior Analytics, Posterior Analytics, Topics and On Sophistical Refutations. One of the principal topics of Aristotle’s focus is syllogism, in which two premises (one major, one minor) lead to a conclusion. This features in Prior Analytics and On Interpretation.

It was with Human, All Too Human, first published in 1878, that Nietzsche developed the aphoristic style that so suited his challenging views and uncompromising style. The text is divided into three main sections: 'Of the First and Last Things', 'History of the Moral Feelings' and 'The Religious Life'.

It can be said of very few books that the world was changed as a result of its publication - but this is certainly the case of Capital: A Critique of Political Economy by Karl Marx (1818-1883). Volume 1 appeared (in German) in 1867, and the two subsequent volumes appeared at later dates after the author's death - completed from extensive notes left by Marx himself.