It is very unfortunate that the philosopher who, as would be generally agreed, has had the greatest influence on modern thought is a writer whose style presents a particularly formidable barrier to the layman, or indeed to any reader tackling him for the first time; and this makes it all the more necessary that an effort should be made by those who have read and studied his works to communicate what they take to be the essential parts of his message. The present article is an attempt to fulfil a part of this function, i.e. to convey a few of the leading ideas of Kant's Critique of Pure Reason, while leaving aside altogether his other writings. I hope Kantian scholars will forgive me if in the attempt to make some of Kant's ideas clear in a very small space to readers who have not specialized in the subject but are interested in philosophy I seem not to do justice to the complexity of his finer distinctions. Also I had better add that this article is simply an attempt to state Kant's doctrine; it is not intended as an expression of my own views, and refrains from criticism.