Here's a great letter by the young Marx to Arnold Ruge from 1843, often published under the name 'For a ruthless Criticism of Everything existing'. I thought it was quite relevant to today's discussions about the Marxism(s) radical self-critique.
For a Ruthless Criticism
The reform of consciousness consists only in making the world aware of its own consciousness, in awakening it out of its dream about itself, in explaining to it the meaning of its own actions. Our whole object can only be – as is also the case in Feuerbach’s criticism of religion – to give religious and philosophical questions the form corresponding to man who has become conscious of himself.
Hence, our motto must be: reform of consciousness not through dogmas, but by analysing the mystical consciousness that is unintelligible to itself, whether it manifests itself in a religious or a political form. It will then become evident that the world has long dreamed of possessing something of which it has only to be conscious in order to possess it in reality. It will become evident that it is not a question of drawing a great mental dividing line between past and future, but of realising the thoughts of the past. Lastly, it will become evident that mankind is not beginning a new work, but is consciously carrying into effect its old work.
In short, therefore, we can formulate the trend of our journal as being: self-clarification (critical philosophy) to be gained by the present time of its struggles and desires. This is a work for the world and for us. It can be only the work of united forces. It is a matter of a confession, and nothing more. In order to secure remission of its sins, mankind has only to declare them for what they actually are.