Added hints to README.md

README.md

@@ -20,43 +20,60 @@ gs psrw.ps
 
 Liked it? Now close the file and reopen it ;-)
 
+_Hint 1_: If you enable the "Watch File" option in `gv`, you will get a
+nice slideshow, for some definition of nice.
+
+_Hint 2_: Running `gv` with `-nosafer -nodirsafe` might be a very bad
+idea.
+
 ## WTF?
 
-Postscript is a Turing-complete language. This means that you can do any
-feasible computation in Postscript. Hence, simulating a random walk in
-Postscript is not a big fuss at all, also because the standard
-Postscript definition already includes a pseudo-random number generator,
-so you don't need to implement it yourself. The only problem is that the
-pseudo-random number generator needs to be initialised with a new seed,
-otherwise you would always visualise the _same_ trajectory.   
+Postscript is a Turing-complete language. This means that you can
+perform any feasible computation in Postscript. Hence, simulating a
+random walk in Postscript is not a big fuss at all, also because the
+standard Postscript definition already includes a pseudo-random number
+generator, so you don't need to implement it yourself. The only problem
+is that the pseudo-random number generator needs to be initialised with
+a new seed, otherwise you would always visualise the _same_ trajectory.   
 
 The simple solution implemented in `psrw.ps` is to store the seed in the
-same file as a comment, and _update_ it after every run.  In a word,
-`psrw.ps` rewrites itself at each run, changing the seed and allowing to
-generate a _new_ random walk trajectory every time you open the file. 
+same file as a comment, and _update_ it at each run.  In practice,
+`psrw.ps` rewrites a slightly modified copy of itself every time you
+"view" it, but a user would hardly notice it :-)
 
 ## Why?
 
-Well, there is no particular reason to write anything like `psrw.ps`. I
-just tried to do something similar around 2001 or 2002, when I was using
-Postscript quite heavily, and at that time I did not find a proper way
-through.  The simplicity of the solution implemented in `psrw.ps`
-scratches a long-standing personal itch, and tells a lot about my poor
-knowledge of Postscript...
+Well, you don't need a particular reason to write anything like
+`psrw.ps`. I just tried to do something similar around 2001 or 2002,
+when I was using Postscript quite heavily, and at that time I did not
+find a proper way through.  So the simplicity of the solution
+implemented in `psrw.ps` scratches a long-standing personal itch, and
+tells a lot about my very poor understanding of Postscript...
 
-## No really, WHY?
+## No seriously, WHY?
 
 I just wanted to make a point about (not) trusting documents written in
 formats that you don't understand, or that are not freely accessible or
-not documented.  Many _text_ formats out there are Turing-complete or
-close-to, and some visualiser (e.g., for PDF or OpenXML) include
-interpreters for other Turing-complete languages (like Javascript or
-VBScript). This mean that they can do almost anything when you "_open_"
-those "_text_" files. 
-
-If it's so easy to craft a document that modifies itself to change a
-comment that you can't visualise, what else can be done by "_text_"
-files saved in proprietary formats?
+are poorly or not documented.  
+
+Many _text_ formats out there are Turing-complete or close-to, and some
+viewers  (e.g., for PDF or OpenXML files) include interpreters for other
+Turing-complete languages (like Javascript or VBScript). This mean that
+these viewers can do almost anything when you "_open_" those "_text_"
+files. The only chance you have is to understand what is going on behind
+the scenes, or to trust the company that provided the smart viewer. But
+can you really trust _them_? 
+
+If it was so easy for a Postscript illiterate like me to craft a
+document that modifies itself by changing _something_ that you cannot
+even visualise, what else can be done by "_text_" files saved in
+proprietary formats?
+
+Well, at this point you should start thinking that you cannot really
+_trust me_ either, even if I sweared that `psrw.ps` does absolutely
+nothing nasty when you "open" it. But how can you be sure I am telling
+the truth? ;-) 
+
 
 ## Links