Some selected quotes, he mentioned himself thinking like a petty-bourgeois intellectual during his years of study. The following quotes are from Talks at the Yenan forum on literature and art on May 1942.

Here I might mention the experience of how my own feelings changed. I began life as a student and at school acquired the ways of a student; I then used to feel it undignified to do even a little manual labour, such as carrying my own luggage in the presence of my fellow students, who were incapable of carrying anything, either on their shoulders or in their hands. At that time I felt that intellectuals were the only clean people in the world, while in comparison workers and peasants were dirty. I did not mind wearing the clothes of other intellectuals, believing them clean, but I would not put on clothes belonging to a worker or peasant, believing them dirty. But after I became a revolutionary and lived with workers and peasants and with soldiers of the revolutionary army, I gradually came to know them well, and they gradually came to know me well too. It was then, and only then, that I fundamentally changed the bourgeois and petty-bourgeois feelings implanted in me in the bourgeois schools.

On the behaviour of petty-bourgeois intellectuals.

The human nature boosted by certain petty-bourgeois intellectuals is also divorced from or opposed to the masses; what they call human nature is in essence nothing but bourgeois individualism, and so, in their eyes, proletarian human nature is contrary to human nature. "The theory of human nature" which some people in Yenan advocate as the basis of their so-called theory of literature and art puts the matter in just this way and is wholly wrong.

On working with petty-bourgeois ideology, I think I was like this initially when I joined my org, I thought to prescribe the lessons I learned in academic institutions.

An ideological struggle is already under way in literary and art circles in Yenan, and it is most necessary. Intellectuals of petty-sour dis ays, i elving tubbary y ta aristil ways, to project themselves and spread their views, and they want the Party and the world to be remoulded in their own image. In the circumstances it is our duty to jolt these "com-rades" and tell them sharply, "That won't work! The proletariat cannot accommodate itself to you; to yield to you would actually be to yield to the big landlord class and the big bourgeoisie and to run the risk of undermining our Party and our country." Whom then must we yield to? We can mould the Party and the world only in the image of the proletarian vanguard.

This one is from his selected works. Here is a link.

The intellectuals often tend to be subjective and individualistic, impractical in their thinking and irresolute in action until they have thrown themselves heart and soul into mass revolutionary struggles, or made up their minds to serve the interests of the masses and become one with them. Hence although the mass of revolutionary intellectuals in China can play a vanguard role or serve as a link with the masses, not all of them will remain revolutionaries to the end. Some will drop out of the revolutionary ranks at critical moments and become passive, while a few may even become enemies of the revolution. The intellectuals can overcome their shortcomings only in mass struggles over a long period.