So I have heard. At one time the Buddha was staying near Rājagaha, on the Vulture’s Peak Mountain. Then, late at night, the Four Great Kings—with large armies of Yaksha, Gandharva, kumbhāṇḍa, and Naga—set guards, troops, and wards at the four quarters and then, lighting up the entire Vulture’s Peak with their beauty, went up to the Buddha, bowed, and sat down to one side. Before sitting down to one side, some spirits bowed, some exchanged greetings and polite conversation, some held up their joined palms toward the Buddha, some announced their name and clan, while some kept silent.

https://suttacentral.net/dn32/en/sujato?layout=plain&reference=none&notes=asterisk&highlight=false&script=latin

The sutta opened with an account of what took place in the spiritual realm. That means it is not visible to ordinary human eyes. But having said that, people in ancient time did reported sightings of strange glows or lights coming from the monastery area whenever some celestial being visited Buddha.

In ancient times, there weren’t any electrical lights and places were dark at night. Buddhist monasteries are located a short distance away from town to be conducive for meditation. Therefore, when strange lights appear in the sky or around the monasteries, it became a talking point for the townsfolk.

Although celestial beings are invisible to ordinary human eyes, there were records in Buddhist sutta whereby visiting gods/goddesses reveal themselves. For example, in a Dhammapada story, Buddha requested a newborn god to appear in front of a congregation and testify how he was reborn in heaven after converting to Buddhism on his deathbed. From this account, Buddhists generally belief we have secured a place in heaven after taking refuge in the Triple Gems. Our only challenge is to go beyond that. (ie. be enlightened)

In another sutta, Buddha had to teach a deva (God) to take on a course body to facilitate communication. Gods from higher heavens have very subtle energy bodies and some are without a gender too.

In this sutta, the gods in concern are from Cāturmahārājika heaven. This is the lowest heaven and closest to Humans. They are defenders and therefore are depicted as wearing military clothing. They report to Sakra, the King of Gods (who reside in a higher heaven named Trāyastriṃśa). And beyond Trāyastriṃśa, there are other higher heavens.

The four heavenly Kings defendTrāyastriṃśa heaven from attacks by Asura. (literally translated as non-god because their behaviour is not in line with a divine being)

From this perspective, Cāturmahārājika heaven appears to be similar to a military outpost that is at the threshold area of Trāyastriṃśa heaven. Interestingly, Asuras were originally inhabitants of Trāyastriṃśa heaven. Unfortunately, they committed some misconduct and were thrown out. In a way, it sounds similar to the story of fallen angels. Since than, the Asura (non-god) had been jealous of the gods and trying to make their way back to heaven.

Based on this understanding, some spiritualists or religious practitioners may unwittingly commune with the Asuras instead of the divine. One of the tell-tale signs is an interpretation of the holy doctrine in a twisted manner, resulting in one turning his back on fundamental values of goodness and preferring righteous violence instead.

Ok, back to this sutta.

The spokesman for this sutta is Vaiśravaṇa of the north direction, king of yakṣas.

He is commonly depicted as holding a huge parasol or spear and a pagoda or mongoose. Buddhists believe that he is also a bestower of wealth. You will usually see his image standing guard at the entrance of a Chinese or Japanese Buddhist temple.

If one is into praying for secular success, it is better to do that in front of the 4 heavenly kings. In the inner hall where Buddha imageries are displayed, it is better to say refuge prayer and reflect on our commitment to become enlightened.

In other words, leave our secular concerns behind at the threshold area.

May all be well and happy.