In AN 5.159
the Buddha explains how the Dhamma should be taught, which starts off by saying that the explanation should be step-by-step.
AN 5.159: Udayi Sutta wrote:"It's not easy to teach the Dhamma to others, Ananda. The Dhamma should be taught to others only when five qualities are established within the person teaching. Which five?
" The Dhamma should be taught with the thought, 'I will speak step-by-step.'
In Ud 5.3
there is a sutta which explains what the components of a step-by-step talk are as given by the Buddha.
Ud 5.3: Kuṭṭhi Sutta wrote:So, aiming at Suppabuddha the leper, he gave a step-by-step talk, i.e., he proclaimed a talk on generosity, on virtue, on heaven; he declared the drawbacks, degradation, & corruption of sensuality, and the rewards of renunciation. Then when the Blessed One knew that Suppabuddha the leper's mind was ready, malleable, free from hindrances, elevated, & clear, he then gave the Dhamma-talk peculiar to Awakened Ones, i.e., stress, origination, cessation, & path.
It's worth noting here that the eightfold path, which is the last of the four noble truths, is not even mentioned until after the earlier steps including virtue have been explained and understood.
The Buddha in AN 8.25
explains that for a lay follower to be virtuous, they follow the five precepts.
AN 8.25: Mahanama Sutta wrote:Mahanama, inasmuch as a lay follower abstains from destroying living beings; abstains from taking what is not given; abstains from sexual misconduct; abstains from lying; and abstains from wine, liquor and intoxicants that are causes for heedlessness; in that way, Mahanama, a lay follower is virtuous.
These quotes combined seem to suggest that the practice of virtue is an early step in the gradual training mentioned in MN 70
MN 70: Kitagiri Sutta wrote:Monks, I do not say that the attainment of gnosis is all at once. Rather, the attainment of gnosis is after gradual training, gradual action, gradual practice.
Also, in SN 55.31
it is explained that a disciple of the noble ones has untorn virtue, which leads to concentration.
SN 55.31: Abhisanda Sutta wrote:Furthermore, the disciple of the noble ones is endowed with virtues that are appealing to the noble ones: untorn, unbroken, unspotted, unsplattered, liberating, praised by the wise, untarnished, leading to concentration.
The importance of virtue as a prerequisite is also discussed in AN 11.2
. Virtue is described as the first step in a series leading to final release.
AN 11.2: Cetana Sutta wrote:For a person endowed with virtue, consummate in virtue, there is no need for an act of will, 'May freedom from remorse arise in me.' It is in the nature of things that freedom from remorse arises in a person endowed with virtue, consummate in virtue.
For a dispassionate person, there is no need for an act of will, 'May I realize the knowledge & vision of release.' It is in the nature of things that a dispassionate person realizes the knowledge & vision of release.
In this way, dispassion has knowledge & vision of release as its purpose, knowledge & vision of release as its reward. Disenchantment has dispassion as its purpose, dispassion as its reward. Knowledge & vision of things as they actually are has disenchantment as its purpose, disenchantment as its reward. Concentration has knowledge & vision of things as they actually are as its purpose, knowledge & vision of things as they actually are as its reward. Pleasure has concentration as its purpose, concentration as its reward. Serenity has pleasure as its purpose, pleasure as its reward. Rapture has serenity as its purpose, serenity as its reward. Joy has rapture as its purpose, rapture as its reward. Freedom from remorse has joy as its purpose, joy as its reward. Skillful virtues have freedom from remorse as their purpose, freedom from remorse as their reward.