From what I've quoted below (I realize I have to change the format here) it can be surmised:
- The "going beyond discrminiation" for which practitioners use koans goes way back in Buddhism - at least as far back as this sutra. True, koans as koans were developed later, but their aim is precisely what is described in this part of the Lankavatara sutra.
- When all is said to be Mind, it's not to say all is unreal.
- "It is to be known by oneself.” There's a lot more here than I'm even scribbling towards.
Here's the quoted text:
1. "The truth-treasure whose principle is the self-nature of Mind, has no selfhood (nairātmyam), stands above all reasoning, and is free from impurities; it points to the knowledge attained in one's inmost self; Lord, show me here the way leading to the Truth...
Come, Blessed One, who art our Teacher, come to Laṅkā on Mount Malaya.
31. "Free from the faults of the philosophers and Pratyekabuddhas and Śrāvakas is (8) the Truth of the inmost consciousness, immaculate and culminating in the stage of Buddhahood.”
38. [After this] the teacher and the sons of the Buddha vanished away in the air, leaving Rāvaṇa the Yaksha himself standing [above] in his mansion.
39. Thought he, "How is this? What means this? and by whom was it heard? What was it that was seen? and by whom was it seen? Where is the city? and where is the Buddha?
40. "Where are those countries, those jewel-shining Buddhas, those Sugatas? (9) Is it a dream then? or a vision? or is it a castle conjured up by the Gandharvas?
41. "Or is it dust in the eye, or a fata morgana, or the dream-child of a barren woman, or the smoke of a fire-wheel, that which I saw here?”
42. Then [Rāvaṇa reflected], "This is the nature as it is (dharmatā) of all things, which belongs to the realm of Mind, and it is not comprehended by the ignorant as they are confused by every form of imagination.
43. "There is neither the seer nor the seen, neither the speaker nor the spoken; the form and usage of the Buddha and his Dharma—they are nothing but discrimination.
44. "Those who see things such as were seen before, do not see the Buddha; [even] when discrimination is not aroused, one does not see1 the Buddha; the Buddha being fully-enlightened is seen where the world itself is not evolved.
The Lord of Laṅkā was then immediately awakened [from his reflection], feeling a revulsion (parāvṛiti) in his mind and realising that the world was nothing but his own mind: he was settled in the realm of non-discrimination, was urged by the stock of his past good deeds, acquired the cleverness of understanding all the texts, obtained the faculty of seeing things as they are, was no more dependent upon others, observed things excellently with his own wisdom (buddhi), gained the insight that was not of discursive reasoning, was no more dependent upon others,2 became a great Yogin of the discipline, was able to manifest himself in all excellent forms, got thoroughly acquainted with all skilful means, had the knowledge of the characteristic aspects of every stage, by which he would surmount it skilfully, was delighted to look into3 the self-nature of Citta, Manas, Manovijñāna, got a view whereby he could cut himself loose from the triple continuation, had the knowledge of disposing of every argument of (10) the philosophers on causation, thoroughly understood the Tathāgata-garbha, the stage of Buddhahood, the inmost self, found himself abiding in the Buddha-knowledge; [when suddenly] a voice was heard from the sky, saying, "It is to be known by oneself.”
"Well done, well done, Lord of Laṅkā! Well done, indeed, Lord of Laṅkā, for once more! The Yogin is to discipline himself as thou doest. The Tathagatas and all things are to be viewed as they are viewed by thee; otherwise viewed, it is nihilism. All things are to be comprehended by transcending the Citta, Manas, and Vijñāna as is done by thee. Thou shouldst look inwardly and not become attached to the letter and a superficial view of things; thou shouldst not fall into the attainments, conceptions, experiences, views, and Samādhis of the Śrāvakas, Pratyekabuddhas, and philosophers; thou shouldst not have any liking for small talk and witticism; thou shouldst not cherish the notion of self-substance,1 nor have any thought for the vainglory of rulership, nor dwell on such Dhyānas as belong to the six Dhyānas, etc.
"Lord of Laṅkā, this is the realisation of the great Yogins: to destroy the discourses advanced by others, to crush mischievous views in pieces, to keep themselves properly away from ego-centered notions, to cause a revulsion in the depths of the mind fittingly by means of an exquisite knowledge. Such are sons of the Buddha who walk in the way of the Mahāyāna. In order to enter upon the stage of self-realisation as attained by the Tathagatas, the discipline is to be pursued by thee.