https://www.marxists.org/archive/lenin/works/1914/cons-logic/ch03.htm

I think this is the passage he's highlighting:

“It will always remain a matter for astonishment how the Kantian philosophy knew that relation of thought to sensuous existence, where it halted, for a merely relative relation of bare appearance, and fully acknowledged and asserted a higher unity of the two in the Idea in general, and, for example, in the idea of an intuitive understanding; but yet stopped dead at this relative relation and at the assertion that the Notion is and remains utterly separated from reality;—so that it affirmed as truth what it pronounced to be finite knowledge, and declared to be superfluous, improper, and figments of thought that which it recognised as truth, and of which it established the definite notion” (26)

In logic, the Idea “becomes the creator of Nature.” (26)