The Perfection of Energy - Mental energy

“As to the word ‘cetasiko’,

this is used in order to show that energy is always mental and that it is not bodily.

There is only mental energy....”
Viriya is nama dhamma (cetasika) which conditions the arising of effort through the body or through citta. Even when we make an effort with the body to do something, we should know that we can make such an effort because of viriya cetasika.
The Commentary refers to the Sutta which deals with someone who makes an alley walk, who is walking up and down, so that he is not indolent or sleepy. From the outward appearance this seems to be bodily energy, but in reality it is because of mental energy, viriya cetasika, that effort through the body can arise.
The Commentary speaks further on about effort which has developed to the degree of the enlightenment factor of viriya (sambhojjhanga), one of the factors pertaining to the realization of the four noble Truths. The Commentary uses the Pali term viriyarambha. Årambha can mean beginning, attempt or effort. Viriyarambha is viriya cetasika, it is the putting forth of energy, such as effort to apply oneself to the Buddha’s teachings. We read further on about the characteristic of energy which should be developed:

“Effort is called ‘arambha’ because it is striving.

The term viriyarambha renders the characteristic of that kind of striving.

What kind of striving?

It is striving by way of escaping from idleness.

Onward effort is so called by virtue of reaching a higher and higher state.

Exertion is so called by virtue of rising up and keeping going.

Endeavour is so called by virtue of special exertion;

zeal, of being zealous;

vigour, of firmness;

fortitude, of bearing (supporting) citta and cetasikas,

or of bearing the continuity of kusala by unbroken procedure.”

These are the characteristics of viriya. It is the escaping from idleness, 

progressing towards a higher state, continued exertion without stopping, zeal and

fortitude in further progress towards the goal.

  We read in the Commentary:

“Another method of exposition:

This viriyarambha is ‘striving’ in expelling lust,

‘onward effort’ in cutting the bonds,

‘exertion’ in escaping from the floods,

‘endeavour’ in reaching the further shore,

‘zeal’ in being a forerunner,

‘ardour’ in exceeding the limit,

‘vigour’ in lifting the bolt (of ignorance),

and ‘fortitude’ in producing steadfastness.

’Verily, let the skin, veins and bones dry up’ -

thus by virtue of unfaltering effort at such time

is the ‘state of a man of unfaltering effort’.”

  The Commentary explains further that energy does not let go of the desire-to-do, chanda (which is necessary to accomplish something), that it does not give up the task, and does not give in to discouragement with regard to the performing of kusala. It uses a simile of an ox which carries a burden and does not let go of it:

“Just as if they were to say,

‘Get a beast of burden, an ox,

to draw a burden from a marshy place not beyond the bullock’s strength,’

and the bullock, pressing the ground with its knees,

were to carry the burden and would not allow it to drop on the ground,

so energy lifts up and seizes the burden in the matter of doing moral acts.

Hence it is said to be ‘support of burden’.”