I undertake the precept to refrain from lying on a high or luxurious sleeping place.
Is that it? Are there any other implications, or guiding spirit above and beyond this? Would e.g. wearing more coarse or unbecoming clothing be in line with this? Would refraining from other such material comforts like couches? Starbucks? Driving a large and impressive vehicle? Shopping for e.g. new clothing?
I have read the shorter and the longer of the “Sabbath” suttas which define the Eight Precepts. I have always thought this one seemed oddly specific!
“Monks, these two slander the Tathagata. Which two? He who explains a discourse whose meaning needs to be inferred as one whose meaning has already been fully drawn out. And he who explains a discourse whose meaning has already been fully drawn out as one whose meaning needs to be inferred…”
Is this a case trying to draw out a teaching which has already been fully expounded? Or is this a teaching which needs to be fully drawn out?
The guiding spirit is renunciation which is the first aspect of right intention/thought.
And what is right thought? Thoughts of renunciation, good will, and harmlessness. This is called right thought.
DN 22
All the examples you gave boil down to “making do with less” and are examples of renunciation for a layperson.
It seems to need further explanation, for example what a “high and luxurious sleeping place” means specifically. The following provides some explanation.
There are some ascetics and brahmins who, while enjoying food given in faith, still make use of high and luxurious bedding. This includes such things as sofas, couches, woolen covers—shag-piled, colorful, white, embroidered with flowers, quilted, embroidered with animals, double-or single-fringed—and silk covers studded with gems, as well as silken sheets, woven carpets, rugs for elephants, horses, or chariots, antelope hide rugs, and spreads of fine deer hide, with a canopy above and red cushions at both ends. They refrain from such bedding. This pertains to their ethics.
DN 2
I think the commentaries (and Vinaya?) go into more detail—maybe someone can provide it? It seems that the bottom line is to sleep in a low and modest place.
Keep in mind that these are precepts that are meant to not be broken. If you expand the meaning, then how to know if you are breaking it or not?
Of course it is beneficial to practice renunciation in all wholesome forms. But I believe that the Buddha created the precepts the way they are so we can know for sure if we are breaking them or keeping them. If he wanted the precepts to include more than they do he could have done that.
Yes, it is possible to reframe the precepts in a more positive way, for example, in AN8.39 they are said to give freedom of fear to others:
Firstly, a noble disciple gives up killing living creatures.
By so doing they give to countless sentient beings the gift of freedom from fear, enmity, and ill will.
To the best of my ability, I will protect and support life and encourage the fulfillment of potential for love and understanding in others.
…
I believe there is a traditional Theravada version, but I can’t locate it right now.
However as Bhante @Snowbird says, the basic training rules such as “not to kill” are very easy to measure. It is very obvious when one breaks it. Keeping them in mind reduces the chance of doing something really bad. “Protect and support”, etc, are good aspirations, but it’s not easy to tell if one is doing these things “to the best of ones ability…”
This got to do with… understanding of sensual pleasures. Also relate to senses restrain when trying to develop samadhi.
what is the gratification of sensual pleasures?
..
Touches known by the body, which are likable, desirable, agreeable, pleasant, sensual, and arousing.
When one lay on comfortable bed, there will arise a feeling of pleasure and enjoyment. Mind tend to go back to enjoy sensual pleasure and drop the samadhi.
This is the reason why if one is training for samadhi avoid all senses pleasure at the beginning.
Though I don’t think this is a practice for common/regular householder when they are still a beginner. For regular householder, 5 precepts should be more than sufficient at the beginning.