What represents a man?
In the context of this question, the word AtmA refers to soul in the sense of what is representative of a person. As with other questions, this is a fairly cryptic question from yama and yudhishThira responds in an equally concise manner.
पुत्र मनुष्यस्य आत्मा
putra manushyasya AtmA.
The son is a man's representation.
Say what? Why is it not the mind or intelligence, or character?
Before we go further, a quick note to avoid unnecessary distractions. The term putra (son) would also apply equally to a daughter in modern norms - so it should be considered a common way of saying (like saying "hey guys" even if this is a mix of boys and girls in a group) than as something discriminatory. Otherwise, the sUtras (verses) will lose their succinctness and every answer - if made politically correct - will be half a page long.
The answer can be looked at in multiple angles. First, a literal translation. Legally (at least in most countries) a son inherits the wealth and debt of the father and so from a social / legal perspective one can say that a son is the representation of the father. Culturally also it can be said that a son is the representation of the father as he has to perform the last rites of the father.
There is also a psychological way to look at this response. We all have a limited lifetime. But our wishes tend to be unlimited, or at least much more than what we can accomplish within that timeframe - much like a huge backlog of items in a software plan that will never get completed in one, two, multiple releases, or ever. Still, we keep adding to the backlog thinking that the features will get done at "some" point! Such is the frailty of human ego. Even though we know that we will never get to something, we can't stop ourselves from adding things to our wish list, making ourselves more miserable - the movies we want to watch, the places we want to go to, the books we want to read, the pleasures we want to get, the money we want to gain, etc. Our biggest weakness is that we keep wanting for things beyond our means.
At some point, we realize that our list is endless and we cannot physically get to the end. We come to a level of awareness of our own mortal limitations and come to grips on what we can accomplish in our lifetime. Do we stop there and be content? No! We now devise (what we think to be) a devious plan!
We think "If I cannot get to things that I desire, then I will get children who can carry out my wishes for me!" Much like a client who want to build a software with poorly stated requirements in a fixed budget and timeline, even though we have no guarantee that our children will carry out our wishes, we keep chugging along with our awesome plan!
Such is our ego that we are not satisfied with the time given to us and want to live beyond our means. While many may deny this, we see this very commonly:
"I couldn't play saxophone - I will send my son to music classes from 3 years old so he becomes Kenny G!"
"I couldn't be a cricket star - I will get my son to training classes so that he becomes the next Tendulkar"
"I couldn't get a comfortable life - I will save all the money, hook or crook, and give a comfortable life for my kids"
We beat ourselves up and we torture our kids with various extracurricular activities all with a hidden desire to make them a better version of us.
We see our kids as an extension of us (and our desires), and that's what yudhishThira conveys here!
This sentiment also present even in modern adages across languages such as बाप का बेटा (baap kA bETA in hindi), அப்பா போல் பிள்ளை (appA pol piLLai in tamizh), like father, like son in English, and so on.
While these may be make sense, these questions are not just meant to be literal. It is said that every verse of mahAbhArata has three meanings - a literal (historic account / story), a psychological (what we discussed above), and philosophical / spiritual.
In order to understand the philosophical / spiritual meaning, one must dig deeper. MahabhArata, where the yaksha prashna comes in, is considered to be the essence of the vedAs. Moreover, in sanAtana dharma or hindu dharma, vedAs (and corresponding literature) are considered the source.
With that in mind, we can take it that yudhishtra is basing this answer not just out of his own creativity, but is referencing the vedA. Which one? The reference in Kaushitaki BrAhmaNa upanishad (12), which is part of Rg Veda, mentions the following:
अङ्गादङ्गाद् संभवसि हृदयाद् अधिजायसे
आत्मा वै पुत्र नामासि सञ्जीव शरदः सतं
angAd angAd sambhavasi
hRdayAd adhijAyase
AtmA vai putra nAmAsi sanjeeva sharadaH satam
(Son), You were born from me limb to limb. You were born from the desires of my heart. You are me only and you now have my name. May you live a hundred harvests (years)
A modern interpretation could mean that a son bears the DNA of his father. The conception of a child happens due the wish of the parents (in general), which is implied by the second phrase - "it comes from the heart".
This verse is also referenced in other places including bhAgavata purANa (10.78.36), bRhadAraNyaka upanishad (6.4.8), and satapata brAHmaNa.
An analogy given to this statement is that a child is like seed that is placed in a pot of soil that then grows into a plant. Without the seed, there is no plant. The pot is a container for the seed.
Now one may make an obvious objection - "That is so sexist. What about daughters? This is so misogynistic and and oppresses and objectifies women as just child bearing machines."
That is a literal take and unfortunately, many translations, especially those that are made by authors of Indian or Western origin without understanding and referencing other texts. The dharmic texts of hinduism is a network of literature that cross-reference each other in many ways and must be taken together to develop an understanding and not separately. It is an interesting mechanism of parity checks to ensure that they are not misinterpreted. The primary responsibility of the teachers (acAryAs and gurus) is to inform the listeners with this consistency.
In this metaphor a mother is like the earth and bears the seed (dhArini - the bearer). Her responsibility is not just to be a container, but to nurture and nourish the seed with the right nutrients (mental and physical) to provide strength and health.
However, for a plant to be healthy, it is not just enough to have good soil. It also needs rain and sunlight to grow. That in turn, is the duty (dharma) of the father. A father should provide the space and the energy or sustenance for the son to hold his roots and grow well.
If the soil is loose (doesn't care) or doesn't have the nutrition (does not provide for physical or mental well being), then the plant will not grow. Similarly, if the plant is not watered adequately (sustenance), sun does not shine, and there is not enough space for the plant to grow, then the plant will be anemic at best and die at worst. Thus, both the mother and the father play a critical role in the development of the child.
Finally, we loop back to the initial explanation. If we our children are the extensions of our desires and if desiring for things beyond our means is wrong, then should we not get any kids and just be content by ourselves?
The answer is a resounding no! As Krishna says in the gIta, not doing your dharma is also adharma. As a human born in this world, one of our svadharmas (inherent duty) is to carry our lineage. So, it is essential that we do our duty (whether we get children or not - that's the result of the actions which we must not covet). And if by chance, we did it out of a mistake (an 'accidental' birth!), we must still do our duty to take care of that child till the child becomes independent.
Thus, in this verse, the meanings are multifold:
A son must support his father - he takes on the wealth and also the debt of the father
He must perform the appropriate rites for his father upon death, as he is a representation of his father
His responsibility is to carry the lineage (or vamsha) of his father
A father in turn, has the responsibility to take care of his son and help him become mentally and physically strong
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