The easiest and the topmost method is to distribute books. Prabhupada says – “What will half an hour lecture do?” But if you can put this literature on the lap of the conditioned living entity, human beings, then these books will act like time bomb. The time bomb explodes when the time is matured, similarly these books, when they will put it in their homes, in their shelves, wherever. One day in life, the human beings will pick up the book because they have spent money on it. So when they pick up this book and read it, at that time, the time bomb will explode in the heart of the living entities and give them proper knowledge about Krishna.
So this is the idea of Srila Prabhupada to distribute books. Just like when a Russian Prime Minister or President or whatever, he wanted to spread Communism in India, so what did he do? He printed unlimited amount of periodicals proclaiming or describing Marxism, Communism and about communists. That magazine was delivered by post to all the individuals, free of charge.

Thus after reading literature, human beings will come to the conclusion that they must chant the holy name of Krishna in this Kali Yuga. So when they chant Hare Krishna, then Krishna from within their heart and Krishna in the form of holy name will revolutionise the society at large.

“तद्वाग्विसर्गो जनताघविप्लवो यस्मिन् प्रतिश्लोकमबद्धवत्यपि ।
नामान्यनन्तस्य यशोऽङकितानि यत् श्रृण्वन्ति गायन्ति गृणन्ति साधव: || “,

even though this Vedic literature, Srimad Bhagavatam is not composed in a proper metre or proper words but because it is glorifying the holy name and past times of अनंत, Sri Krishna, it will invoke revolution into the heart and society at large.
So this is the idea, this literature is about Krishna, His pure devotees and the interaction between them. When we distribute such literature, then it will revolutionise, it will bring revolution in the human society, a Krishna Conscious revolution and that’s why we distribute Prabhupada’s books.