TRANSLATION

" 'Whatever result was obtained in Satya-yuga by meditating on Visnu, in Treta-yuga by performing sacrifices and in Dvapara-yuga by serving the Lord's lotus feet can also be obtained in Kali-yuga simply by chanting the Hare Krsna maha-mantra.'

This verse is quoted from Srimad-Bhagavatam (12.3.52). At the present moment in Kali-yuga there are many false meditators who concoct some imaginary form and try to meditate upon it. It has become fashionable to meditate, but people know nothing about the object of meditation. That is explained here. Yad dhyayato visnum. One has to meditate upon Lord Visnu or Lord Krsna. Without referring to the sastras, so-called meditators aim at impersonal objects. Lord Krsna has condemned them in Bhagavad-gita (12.5):

kleso 'dhikataras tesam
avyaktasakta-cetasam
avyakta hi gatir duhkham
dehavadbhir avapyate

"For those whose minds are attached to the unmanifested, impersonal feature of the Supreme, advancement is very troublesome. To make progress in that discipline is always difficult for those who are embodied."

Not knowing how to meditate, foolish people simply suffer, and there is no benefit derived from their spiritual activities. The same reference can be found in the following verse from the Visnu Purana (6.2.17), Padma Purana (Uttara-khanda 72.25) and Brhan-naradiya Purana (38.97).