These three selections, two from the short prajnaparamita sutras, and the last from the sandhinirmocana sutra cover a lot of territory in a short time and provide a good glimpse into the depth and basics of these mahayana sutras. These are also fairly uncommonly known. Note that I selected parts that could for the most part stand alone without context, but they will likely lack the 'flow' of the sutra that contains them.
The enlightenment being (bodhisattva) named Vajrapani questioned the Buddha on Vulture Peak.
Vajrapani: How should an enlightenment being train in the perfection of wisdom?
Buddha: The enlightenment being should train in perfection of wisdom through the non-production of all things. Furthermore, he or she should train in perfect wisdom through the fact that all things, form, etc, are empty of own being, devoid of signs, without existence, and cannot be apprehended. He or she should train in perfect wisdom through the emptiness of the subject, the object, existence, (etc.), and through the emptiness of non-existence. Vajrapani, this perfection of wisdom is the mother of all buddhas.
The enlightenment being named Subhiti questioned the Buddha on Vulture Peak
Subhuti: World honored one, it is indeed difficult to get to the bottom of this perfection of wisdom.
Buddha: Subhuti, this is because the perfection of wisdom is completely isolated.
Subhuti: World honored one, this perfection of wisdom is indeed hard to fathom.
Buddha: Subhuti, this is because the perfection of wisdom is absolutely pure.
Subhuti: World honored one, can’t this perfection of wisdom be likened to empty space?
Buddha: Because, Subhuti, the perfection of wisdom is absolutely clear. In this way it can be said to be like empty space.
Subhuti: Alas, world honored one, isn’t this perfection of wisdom indeed difficult to understand for someone who does not practice?
Buddha: Indeed, it is as you say Subhuti. It is difficult for one to gain confidence in this perfection of wisdom if he or she has limited wholesome roots, is of little mental power, is aimless, has learned little, relies on bad spiritual teachers, is not inclined to ask questions, is endowed with little faith, is lazy, has little power of compassion, has inferior resolve. This is why it is hard to gain confidence in this perfection of wisdom.
But he or she that has resolute intention, who wants to quickly know the utmost, right and perfect enlightenment should constantly hear this perfection of wisdom, take it up, bear it in mind, and master it. In this way they will know the utmost, right and perfect enlightenment.
An enlightening being named ‘Born of Ultimate Truth’ questions the Buddha.
Born of Ultimate Truth (Bodhisattva) asks:
The Buddha says that all things have no essence, no origin or extinction, that they are fundamentally quiescent and inherently nirvanic. I wonder, what is the inner intent, the inner basis when you say all things have no essence, no origin or extinction, that they are fundamentally quiescent and inherently nirvanic? Please be so compassionate as to explain the hidden meaning of this."
The buddha answers:
Good, good! Your reflections are most reasonable. It is good that you are able to ask about this profound matter. You have asked this question because you want to aid and comfort innumerable beings, because you have compassion for the world and want to foster their welfare and happiness. Listen closely, and I will explain for you the inner intent
of the saying that all things have no essence, have no origin or extinction, are fundamentally quiescent and inherently nirvanic. You should know that when I say all things have no essence,
I am alluding their to three kinds of emptiness: emptiness of characteristics, emptiness of birth, and ultimate emptiness. "What is the emptiness of characteristics of all things? It is their conceptually grasped character. Why? Because the characteristics are defined by artificial names, not by inherent definition. Therefore this is called emptiness of characteristics. What is the emptiness of birth of things? It is the dependently originated character of things. Why? Because they exist dependent on the power of other conditions and do not exist of themselves. Therefore this is called emptiness of birth.
"What is the ultimate emptiness of things? It means that things are said to be emptiness because of the emptiness of birth; that is to say, the fact of dependent origination is also called ultimate emptiness. Why? I reveal the pure object of attention in things to be ultimate emptiness. Dependency is not a pure object of attention, so I also call it ultimately essenceless. There is also the perfectly real character of things, which is also called ultimate emptiness. Why? Because the selflessness of all things is called ultimate truth and can also be called emptiness. This is the ultimate truth of all things and is revealed by emptiness, so for these reasons it is called ultimate emptiness.