Get down to business, all of you! You will have capitalists beside you, including foreign capitalists, concessionaires and leaseholders. They will squeeze profits out of you amounting to hundreds per cent; they will enrich themselves, operating alongside of you. Let them. Meanwhile you will learn from them the business of running the economy, and only when you do that will you be able to build up a communist republic. Since we must necessarily learn quickly, any slackness in this respect is a serious crime. And we must undergo this training, this severe, stern and sometimes even cruel training, because we have no other way out.

You must remember that our Soviet land is impoverished after many years of trial and suffering, and has no socialist France or socialist England as neighbours which could help us with their highly developed technology and their highly developed industry. Bear that in mind! We must remember that at present all their highly developed technology and their highly developed industry belong to the capitalists, who are fighting us.

We must remember that we must either strain every nerve in everyday effort, or we shall inevitably go under.

https://www.marxists.org/archive/lenin/works/1921/oct/17.htm