With the efflux of time, the practice of dharma undergoes certain changes and this is well recognized in the dharma SAstras.
As the yugas change, the yuga dharma also changes as determined by the great Rishis. Accordingly, the major shift has happened as follows in the four yugas:
Kruta yuga = DhyAnam
TretA yuga = YAga
dvApara yuga = PUjA
Kali yuga = nAma sankIrtanam (keSava)
dhyAyan krute yajan yajnaih tretAyAm dvAparercayan !
yadApnoti tadApnoti kalau sankIrtya keSavam !!
YAvanna kIrtayet rAmam kalikalmasha sambhavam !
tAvattishthati dehesmin bhayam cAtra pravartate !!
SrutismrutipurANeshu rAma nAma samIritam !
tannAma kIrtanam bhUyas tApatrayavinASanam !!
---- cyavana smruti
sarvapApa prasaktopi dhyAyannimishamacyutam !
punastapasvI bhavati panktipAvana pAvanah !!
na tAvatpApamedhena yannAma hatam hareh !
atireka bhayAdAhuh prAyascittAntaram vrithA !!
prAyascittAnyaSeshANi tapah karmAtmakAni vai !
yAni teshAmaSeshANAm krishNAnus smaraNam param !!
----SrI vishNu purANa
One should not condemn the changing yuga dharmas and those dvijas who follow those, as the dvijAs are suited to the yuga concerned.
yuge yuge ca ye dharmAs tatra tatra ye dvijAh !
teshAm nindA na kartavYA yugarUpa hi te dvijAh !!
krute tu mAnavA dharma: tretAyAm gautamA: smrutAh !
dvApare SAnkha likhitAh kalau pArASarAh smrutAh !!
It is said that Manu smruti is applicable in Kruta yuga, Gautama smruti in tretA yuga, Sankha and Likhita smrutis in dvApara yuga and ParASara smruti in kali yuga.
Let us take the case of performance of SrAddha and see whether we can go fully by only what is stated in ParASara Smruti. But ParASara smruti does not deal with the elaborate provisions regarding performance of SrAddha. A smruti is like a policy document. Only in the grhya sUtras, the detailed procedures are explained. We cannot ignore what is said by the sUtrakAras. The Sraddha prayoga that we practise today is a digested form based on various relevant smrutis and the sUtras. Hence we have to take this as the benchmark and try to follow to the extent possible.
It is to be noted that in many places what we find is that the smrutis differ in the subtle aspects of performance of samskAras, karmAnushtHAnas and so on depending on the yuga dharma about which only the great Rishis deeply know. If a particular aspect has not been dealt with in a smruti, but is contained in another smruti, it can be considered for guidance. There are areas of conflicts as well. All these call for proper reconciliation and resolution by experts in dharma SAstras from time to time. Hence we have to go by what is based on traditional practice wherever there is conflict in the statement of the various smrutis.
kalau kalmasha chittAnAm pApadravyopa jIvinAm !
vidhikriyA vihInAnAm gatir govinda kIrtanam !!
nama: parama Rishibhyo nama: parama Rishibhyah !