Why it is not advised to perform other Yugas activities into a particular Yuga?

Question

This answer says very well that it is as it is stated but does not explain why.

https://hinduism.stackexchange.com/a/44173/22667

Quot. Rickross user says: " Now, since this very nature of the fact, that 3 out of the 4 pillars of Dharma are non-fuctional in Kali Yuga, can't be changed by anybody among us shows no matter how much we try we can't follow a Satya Yuga lifestyle in the Kali Yuga. Because the nature of the Yuga itself is such that it does not have all the pillars of Dharma intact in it.

So, it is neither possible nor desired according to me. Because Yuga Dharma has to prevail."

Through Manu Smrtris which are the Laws. Yet laws not always explain "why" but other Shastras probably do.

Therefore:

Why Kali Yuga has to prevail?

What happens if I chant Treta or Krita [Satya] Yugic mantras during this very period of this Yuga?

Are Vedas to be read less or mantras to be chanted or listened or read less or in a certain other way? And which one way?

Last but not least: Existentialist question

Yuga determine us humans or we determine Yuga itself?

Many more you can say. Your suggestions are very much required in this area.

Thank you

Answer 1

Why kali yuga has to prevail? And Yuga determine us humans or we determine yuga?

Looking forward for others view and answer of this question, I will choose rather weird way to answer it.

In shri surya siddhanta, chapter 1: on mean motions of planets,

5. Thine intent is known to me; I am gratified by thine austerities; I will give the science upon which time is founded, the grand system of planets.

It's pretty clear, the motion of the planets have been used to divide time into the yugas. Following the siddhanta go on explaining how time is represented for god, demons and Bhramha. The yugas are separated here:

17. The tenth part of age (caturyuga) multiplied successively by four, three, two, one gives length of golden and other ages.

This shows us that however we view it, the yugas prevail as they occur due to planetary motion itself. But it also follows that the events that happen in each yuga are already predetermined. Why is that? Probably no one knows. So yugas are not determined by us, since the revolution is controlling it. Do yuga determine us, probably yes. Its pretty clear that yugas are not identical in first place, each consists of diffrent amounts of time. Satya yuga being the longest and kali to be smallest.

What happens if I chant Treta or krita yuga mantras during this very period of yuga?

I dont know or I dont think a mantra can be classified according to yugas. What about 'om', which yuga it comes from. Mantras must be classified according to their Gunas only.

But there are certain restrictions on 'yagnya', in Sarvollāsatantram,

अनुकल्पं कलौ देय॑ पशुमात्रं विशेषकम्‌ । अश्वमेधं कलौ भद्रे द्रव्याभावे परित्यजेत्‌ ॥ ११ ॥

It says the ashvamedh yagnya over the purpose of gaining 'dravya' must not be performed ( intact its restricted- 'varjit')

Are vedas to be read less...

Note that Different texts will encourage different things, from Sarvollāsatantram

अथ युगभेदे शास्त्राचरणम्‌-- सत्ये श्रुत्युक्तकर्माणि त्रेतायां स्मृतिसम्मतम्‌ । द्वारे च॒ पुराणानि कलावागमसम्मतम्‌ ॥

It says in satya yuga- karma as per vedas, in treta as per smriti, in dwapar as per purana, in kalikal as per Agamas.

Why it is not advised to perform other Yugas activities into a particular Yuga?

As @Rickross already has answered it, in kali yuga bull stands on one leg, bull barely can stand and Dharma falls apart in kali yuga. We always need change as per situation, and thus then our activities must differ.

Answer 2

It is not advised because it is not practically possible.

Manu Smriti says:

1.85. One set of duties (is prescribed) for men in the Krita age, different ones in the Treta and in the Dvapara, and (again) another (set) in the Kali, in a proportion as (those) ages decrease in length.

1.86. In the Krita age the chief (virtue) is declared to be (the performance of) austerities, in the Treta (divine) knowledge, in the Dvapara (the performance of) sacrifices, in the Kali liberality alone.

The Dharma for Krita is therefore performance of austerities (Tapas) which isn't possible without Indriya Nigraha and restraint in eating for a long period of time.

But the nature of Kali Yuga is such that beings of this age are dependent on food. They are also attracted towards sensual pleasures to a great extent. So, naturally it is not possible for them to follow the Dharma of Krita Yuga.

But since the men of the Kali Age are full of greed, lust, gluttony, they will on that account neglect sidhana and will fall into sin, and having drunk much wine for the sake of the pleasure of the senses, will become mad with intoxication, and bereft of all notion of right and wrong (61). Some will violate the wives of others, others will become rogues, and some, in the indiscriminating rage of lust, will go (whoever she be) with any woman (62). Over eating and drinking will disease many and deprive them of strength and sense.

(Mahanirvana Tantra's Chapter 1 verses)

Also, from Parashara Smriti:

32. '' Life in the Krita has its seat in the bones ; in the Treta it has its seat in the flesh ; in the Dvapara the blood is the seat of life ; in the Kali, however, life is dependent upon food and the like.

33. " Special are the rules of conduct for each cyclical age ; and the regenerate castes are guided by the rules that govern the age ; no censure (therefore) can attach to them ; for the regenerates conform to the spirit of the age."

(from Chapter 1)

Thus, if someone in Kali Yuga tries to adopt the practices of other Yugas he might fall ill and thus damaging his prospect as a spiritual aspirant. Therefore, what is best for him has been recommended for him in the scriptures.