"All our external perception presupposes, firstly, an activity of the mind which is checked and which we call sensation; secondly, an activity of the mind which gives to this felt sensation an infinitely divisible extension and which we call contemplation; and, thirdly, an activity of the mind which objectivates the thus extended sensation and asserts it to be an external thing, and which we call thinking." 'Facts of Consciousness' is a book on the human mind and its abilities in perception of information. It is the work of 17th century German philosopher Johann Gottlieb Frichte.