Subsist derives from Latin literally meaning to stand still or to remain. Sub means "under", and sistere means "to stand" or "to place"; imagine placing a piece of paper under a weight so that it does not leave.
Subsist is generally used to indicate survival on a minimum of resources, but can also be used to indicate something continues (retaining a certain state) or even just exists. In your example, subsist seems to be used to indicate persistence. The "art of law" continues, or survives in the accumulated experience and expertise.
Note that subsist does not require a complement. You can simply say "The art of law subsists." In your example, the complement "in" was added to indicate where the art of law persists.
In contrast, consist derives from Latin literally meaning to stand together. Con- derives from the Latin cum, meaning "with" or "together," and again sistere means "to stand."
Consist is used to indicate either what a subject is composed of, or what it is comprised in.
In its modern usage, consist always requires a complement indicating either what the subject is composed of, or what the subject is included within.
Consist also has an older definition allowing it to indicate that something simply exists, but this is an obsolete use of the word.
From Webster's Revised Unabridged Dictionary (1913):
To Consist, Consist of, Consist in. The verb consist is employed chiefly for two purposes, which are marked and distinguished by the prepositions used. When we wish to indicate the parts which unite to compose a thing, we use of; as when we say, Macaulay's Miscellanies consist chiefly of articles which were first published in the Edinburgh Review." When we wish to indicate the true nature of a thing, or that on which it depends, we use in; as, There are some artists whose skill consists in a certain manner which they have affected." Our safety consists in a strict adherence to duty."
See also Dictionary.com:
Consist verb (used without object)
-
to be made up or composed (usually followed by of):
"This cake consists mainly of sugar, flour, and butter."
-
to be comprised or contained (usually followed by in):
"Her charm does not consist only in her beauty."
I would go with something similar to J.R.'s suggestion:
It contains all the information on what one is thinking about.
Prepositions on or about are commonly used (with information) to convey that the thing mentioned has something as a topic (see ODO def 3).
Since you already have one about used at the end, to avoid repetition you can go with on and get the same meaning.
Example of such usage:
The pamphlet provides a lot of information on recent changes to the tax laws.
From: M-W
An aside: this Google Ngram gives a rough image of how often information on is used.
"Information that tells" is not ungrammatical, but it sounds unidiomatic to me.
Best Answer
The three verbs have almost the same meaning. So what is the difference? The only difference is that the three Latin verbs come from three different simplex verbs (verbs without a prefix).
contain comes from Latin ten-é:re meaning to hold. A whole can "hold" several elements together. Latin con- meaning together.
include comes from Latin claud-ere/clud-ere to close. To include meaning to close in. A whole can "close in" several elements just as a city wall closes in a lot of different buildings. English to close is related with the third stem claus-um of claudere.
To consist comes from Latin si-st-ere, itself a derivation of Latin stare/stere meaning to stand. The Latin prefix con- often means together. So if you say "The whole consists of several parts" you actually say "Several parts stand together and form a whole".
So all three verbs express the same meaning. But language can express one idea with different words.