If the mind is not pure, then the marks are not pure.

The Vimalakīrti Nirdeśa Sūtra says: 随其心净则佛国土净。If the mind is not pure, then the Buddha-land is also not pure, because when the view is not pure, the appearances are not pure—how could the land be pure? If the mind is not pure, how could there be a pure Buddha-land? Indeed, only when the mind is pure can the view be pure, and only when the view is pure can the appearances be pure. Ordinary sentient beings whose minds are not pure have impure views, and thus the appearances they perceive cannot be pure. Therefore, when sentient beings see the Buddha, they will also regard the Buddha as being just like themselves, having the afflictions of greed, hatred, and delusion; they will even pick out all kinds of faults in the Buddha, perceiving the Buddha's pure conduct as defiled conduct. For example, there was a woman of a non-Buddhist path who came to listen to the Dharma at the Buddha's Dharma assemblies. Every time she was the last to leave, and in the morning she was the first to arrive at the assembly, which led everyone to misunderstand that this woman was living together with the Buddha. Several months later, she placed a wooden basin on her belly to pretend she was pregnant. When everyone saw this, they all believed that the Buddha had indeed had an affair with this woman, and there was much gossip. Later, the Four Heavenly Kings could no longer bear to watch, so they transformed into a mouse that gnawed the wooden basin to pieces, and it fell out. Only then did everyone suddenly realize the truth.

If sentient beings truly understood the Buddha and had faith in the Buddha, could they harbor a divergent mind and doubt the Buddha? In the final analysis, it is still that sentient beings' inner minds are filthy and defiled, and they themselves assume the Buddha would do such a thing. Those disciples with pure minds would never raise any objection or show any disrespect toward the Buddha; they would completely and thoroughly trust the Buddha's purity. Whatever kind of mind sentient beings have, that is the kind of appearance they will recognize—they will not go beyond the cognitive scope of their own minds. Therefore, a person whose mind is defiled does not believe that anyone could have an extremely pure mind; when others' conduct and views are inconsistent with their own, they become suspicious upon encountering anything, and they do not even need to become suspicious—they directly confirm the other's fault. From this example, we can see that sentient beings' minds are indeed filthy and defiled, lacking correct knowledge and view. 

When a person with a pure mind encounters a matter, it simply passes and is done with, without dwelling on thoughts. A person whose mind is not pure has all kinds of speculations, all kinds of views, and all kinds of doubts lying across the chest, unwilling to let go; winds of gossip and dispute arise, and conflicts abound. That is why the secular world is in chaos every day, with no days of peace. From families to society, groups large and small are all like this. The reason is that sentient beings' minds are too filthy, their defilements too severe, and their misunderstandings too many—hence the abundance of disputes.