Abstract art is very difficult of understand. Post-modern art asks a lot to its audience.
Borges is a novelist and a poet. He is interested in the act of creation. "The Other Tiger" is a symbol for the creative act. The alter tiger skips other visions of the tiger. Which is the original tiger? This is a research question that starts a debate: why are artists attracted and scared about features of the tiger?
The tiger somehow  represents the concept of sublime where emotions seem xcontradictory: you are both attracted and scared by the tiger and this makes it a sublime experience.
Longino is the first person that studied the sublime.
Edmund Burke, during the Romantic period, was interested in the sublime: he wanted to find explanation about why human beings are both fascinated and scared by someone or something. In a way or another the sublime is seductive.
Seduction brings somebody somewhere else, in an alter dimension. You can't touch it. It depends on your vision of things.
The limits of art creation are connected to the limits of the creator's vision.
A vision brings forth  the other tiger: an alter tiger, different from the common tiger (vision of everybody).
It discusses the possibility of art to create something which has no concrete reference point, but it exists in the mind as an abstract potential and possibility.
Creation is at the centre of any great literary man's research. Post-modern art is mainly abstract art. It is conceptual and therefore sometimes if not often disorienting: It seems tojuxtappose discordant things. The meaning has to be given by the watcher. There is no guide.
Post-Modernism is a cultural attitude that still goes on. The suffix -ism (like Modernism, Romanticism, Realism) carries a negative attitude that cultural movements have when they areborn. It is a semantic negative part of the word adopted when a cultural or artistic movements is new and therefore it has not yet clear. People do not comprehend some of its features. People were used to think according to existing conventions and and to follow tradition which gives us security. Habits shape our life. People are afraid of difference, because  it perturbs, unhinges the system [Freud called such experience Das Unheimlich ]
Post-Modernism is indebted to mostly philosophical research developed in the 60s both at Berkley University (in the USA) and Surbone University (in Europe).
Philosophical research brought with 1968 revolution: in the Sixties inside  the universities the main point questioned was the concept of AUTHORITY: where authority came from and therefore what gives human being the sense of what is right and what is wrong? This explains why the word author was no longer fashionable and was replaced by different words. The concept of author  became connected to the kind of textype (rather than the one of authority). So you had: novelist, poet,  writer, playwright and so on.
Author implies somebody  creates his work ab nihilo.  
All works of art are the product of intertextuality, which implies a silent dialog between different texts from different art works being the product of culture.
All Post-Modern art defeated the concept of a centre (also a representation of authority).
Technology gave a great hand to Post-Modernism. It fostered reflection of the concept of centre reinforcing the idea that there is no one centre but rather many centres. There are many words that have different centres and these centres create a network of meanings and texts. The centres are named nodes and create the idea of global connections. The network breaks whenever a node breaks.
This implies interconnection and intertextuality as an icon of the way relationship are born.
The nodes of different centres  keep the system together. Human being must therefore be decentred.
What has all this to do with literature?
There are no origins, there is only production, and we (human beings) produce our selves (identity) in language: we are not what we speak, we are rather what speaks us [this is called semiotic materialism].
This explain why international diplomacy is very important to keep balance, to keep peace..

One single authority (the truth, the centre) was no longer considered  the proper way to approach life. There were many centres connected in a network.
Art production is food for thought because it always provides new representations of existing experience.
It puts into discussion and undermines the concept of truth (philosophical perspective). This implies the crash of all definite values.
In the humanities any form of hierarchy between high culture and low culture was rejected.
Post-Modernism makes no difference between high art and low art. Art becomes inclusive of different media, languages. An artefact (work of art) has no origins. There is not a single art that is creates ab nihilo, this also explains for the frequent adoption of the word intertextuality, the fashion of collage, the concept of hybridity which implies assembling things which apparent have no similarities. A hybrid is a fusion of different forms. Hybridity blurs the traditional distinction between paintings, cultures, films. Installations were first considered hybrid art forms . It often includes several difference media such as painting, photography, film.
This creates a complex idea of society, in that in several cases common people are unable to find a link between all that, a link from the traditional point of view because traition elicits people  to think according to logical threads.
Art is a form of communication. It should put something in common  between sender and audience (form of communication). It stays in a similarcontext (con = together).
All this has something to do with instability of signifier which is the surfer meaning and of signified which is the name slip according the context it is introduced. Language is dynamic, there is no one single meaning.
Culture is a crossroads of codes.
The position of the reader depends on his cultural encyclopaedia.
If I give the common people no security, people might either feel loss or try to integrate and therefore become eager to find out the multiplicity of meanings, which implies A de-centring process.
The individual becomeS scared, weak (THE SOCALLED iTALIAN PERNSIERO DEBOLE).Human beings have to find a meaningful definition of the sense of life on their own
.It is not casual that research goes together with discovery. The are only  unstable positions because research means "to  go back" and discover means "take the cover away ".
Post-Modernism made the concept of truth crumble. You feel displaced. Today research is complex and this makes us marginal.
The human condition is extreme precarious. Many difference defensive weapons are employed by human beings in front of such fragmentary world  and anybody among us can develop personal defensive weapons.
Lyotand spoke about a belief of tradition (God, Perfection, Truth, Pope, Christianity): different  ways to tell and explain the World. There are as many histories as many historians telling their version of history and therefore the  
individual is never in full grasp of his/her identity, because one's identity slips. according to position, context and relationships.

Post-Modern art is a comprehensive, umbrella term continually opening and widening its bounderies. it follows that  the concept of limit is a mental process. This is also a reaction to modernism which was worried about finding a sense, a truth.