Before coming across the Saundara-nanda of Aśvaghoṣa, I had read about the four dhyānas, or stages of sitting-meditation, but hadn't found any satisfactory description of them.
Representation of ancient Indian words by Chinese pictographs is liable to raise more questions than it answers. It has struck me forcibly in recent days that if we translate both dhyāna and bhāvanā as "meditation," we are in danger of creating the same kind of confusion in English (which we needn't do, because English, like Sanskrit, is more amenable than Chinese and Japanese to saying what needs to said, be it ambiguous or unambiguous). Cultivating gladness, for example, is one thing. Sitting-dhyāna is another thing. Except there may be instances where they are one and the same thing. But that might be a topic for another post.
A cause (nimittam?) of great gladness, as far as I am concerned, is that in the Sanskrit of Aśvaghoṣa we have got a seminal description, which is very clear, of what the four dhyānas are -- or at least, more to the point, what their gist is, what their direction is.
Sprung free from pernicious theories,
Seeing an end to becoming,
And feeling horror for the consequences of affliction,
Nanda trembled not at death or hellish realms.
As full of skin, sinew, fat, blood, bone, and flesh,
And hair and a mass of other such unholy stuff,
He then observed the body to be;
He looked into its essential reality,
and found not even an atom.
He, firm in himself,
minimised the duality of love and hate
By the yoke of that very practice.
Being himself big across the chest,
he made those two small,
And so obtained the second fruit in the noble dharma.
A small vestige of the great enemy, red passion,
Whose straining bow is impatient desire
and whose arrow is fixity,
He destroyed using weapons
procured from the body as it naturally is --
Using the darts of the disagreeable,
weapons from the armoury of practice.
That gestating love-rival, malice,
Whose weapon is hatred
and whose errant arrow is anger,
He slayed with the arrows of kindness,
which are contained in a quiver of constancy
And released from the bow-string of patience.
And so the hero cut the three roots of shameful conduct
Using three seats of release,
As if three rival princes,
bearing bows in the van of their armies,
Had been cut down by one prince using three iron points.
In order to go entirely beyond the sphere of desire,
He overpowered those enemies that grab the heel,
So that he attained, because of practice,
the fruit of not returning,
And stood as if at the gateway to the citadel of nirvāṇa.
Distanced from desires and tainted things,
Containing ideas and containing thoughts,
Born of solitude and possessed of joy and ease,
Is the first stage of meditation, which he then entered.
Released from the burning of the bonfire of desires,
He derived great gladness
from ease in the act of meditating --
Ease like a heat-exhausted man diving into water.
Or like a pauper coming into great wealth.
Even in that, he realised, ideas about aforesaid things,
And thoughts about what is or is not good,
Are something not quieted,
causing disturbance in the mind,
And so he decided to let them go.
For, just as waves produce disturbance
In a river bearing a steady flow of tranquil water,
So ideas, like waves of thought,
Disturb the water of the one-pointed mind.
Just as, to one who is weary, and fallen fast asleep,
Noises are a source of bother,
So, to one indulging in his original state
of unitary awareness,
Ideas become bothersome.
And so gradually bereft of idea and thought,
His mind tranquil from one-pointedness,
He realised the joy and ease born of balanced stillness --
That inner wellbeing
which is the second stage of meditation.
And on reaching that stage, in which the mind is silent,
He experienced an intense joy
that he had never experienced before.
But here too he found a fault, in joy,
Just as he had in ideas.
For when a man finds intense joy in anything,
Paradoxically, suffering for him is right there.
Hence, seeing the faults there in joy,
He kept going up, into practice that goes beyond joy.
And so experiencing the ease enjoyed by the noble ones,
from non-attachment to joy,
Knowing it totally, with his body,
He remained indifferent, fully aware,
And, having realised the third stage of meditation,
Since the ease here is beyond any ease,
And there is no progression of ease beyond it,
Therefore, as a knower of higher and lower,
he realised it as a condition of resplendent wholeness
Which he deemed superlative -- in a friendly way.
Then, even in that stage of meditation, he found a fault:
He saw it as better to be quiet, not excited,
Whereas his mind was fluctuating tirelessly
Because of ease circulating.
In excitement there is interference,
And where there is interference there is suffering,
Which is why, insofar as ease is excitatory,
Devotees who are desirous of quiet give up that ease.
Then, because he had let go of ease and suffering,
And of working on the mind, already,
He realised the lucidity
in which there is indifference and full awareness:
Thus, beyond suffering and ease,
is the fourth stage of meditation.
Since in this there is neither ease nor suffering,
And the act of knowing abides here, being its own object,
Therefore utter lucidity
through indifference and awareness
Is specified in the protocol
for the fourth stage of meditation.
Consequently, relying on the fourth stage of meditation,
He made up his mind to win the worthy state,
Like a king joining forces with a strong and noble ally
And then aspiring to conquer unconquered lands.