In plain words
It must become a heart of joy. Only then will this pure Ātmatattva be easily understood by him. Having understood the Ātmatattva in this way, he becomes fit to teach it to others. Not by learning alone, nor by scholarship, nor again by the power of intellect is it to be gained, this Ātmatattva. For this, purity of citta alone is essential. Rāmakṛṣṇa Paramahaṃsa, Kabīr, Sūradās, and all such people: what learning did they acquire? What great power of intellect was there in them? No scholar, an unlettered man: that was Rāmakṛṣṇa Paramahaṃsa. Yet the name of that unlettered Rāmakṛṣṇa Paramahaṃsa shines out brilliantly today in the wide world: what is the reason for this? Purity of citta alone is its root cause. That is precisely why: ‘Natapāya, natīrthānāṃ, naśāstrāṇa japānahi saṃsāra sāgaroddhāre sajjanaṃ sevanaṃ vinā.’ To gain such purity of citta you need not do tapas. You need not read the Vedas and śāstras, the Itihāsas and Purāṇas. You need not do any japa or any dhyāna. If you remember God in your heart constantly, with Prema, there is no other sādhana greater than this.
Food alone is the root cause of the power of Manas
Only a heart that holds Prema is a truly human heart. If such a heart of Prema is to grow in us, sacred and pure food and drink are essential for it. The food you eat, you cast out in its gross form as excrement. Food in its subtle form takes shape in man's body as muscle and as blood. The subtlest food alone turns into Manas. So food alone is the root cause of the power of Manas. As the food, so the Manas. So it is essential to eat food that is sāttvic, sacred, wholesome and moderate. In ancient times the great ṛṣis left the villages, left the hamlets, and living in deep forests and eating roots and tubers, they passed their lives in Praśānti. You do not know the sāttvic quality that is in those roots and tubers. Rāma, Lakṣmaṇa and Sītā wandered in the forest, eating those fruits of the forest, and they enjoyed great Ānanda.