What does "About its lot" mean?

Question

In Douglas Adams' Dirk Gently's Holistic Detective Agency, Chapter 2, when talking about how long the Electric Monk believed silly things, the book says:

How long did the Monk believe these things?

Well, as far as the Monk was concerned, forever. The faith which moves mountains, or at least believes them against all the available evidence to be pink, was a solid and abiding faith, a great rock against which the world could hurl whatever it would, yet it would not be shaken. In practice, the horse knew, twenty-four hours was usually about its lot.

I think the last sentence basically says that the Monk had believed for about twenty-four hours, but I'm not sure about the usage of "about its lot". What is the "lot" referring here, or is it some kind of idiom I'm missing? Googling it returned some vague Bible references and it doesn't seem to be what I'm looking for.

You can find the whole chapter here, if it helps at all.

Answer 1

The word lot as intended by Adams in your quote, has a meaning that falls somewhere between those listed as 3a and 3b in Merriam-Webster's Eleventh Collegiate Dictionary (2003):

lot n (bef. 12c) 1 : an object used as a counter in determining a question by chance 2 a : the use of lots as a means of deciding something b : the resulting choice 3 a : something that comes to one upon whom a lot has fallen : SHARE b : one's way of life or worldly fate : FORTUNE

The "lot" of the Monk's faith in a particular thing is in one sense the share that comes to that faith in his active belief system, and in another sense it is the fate of that faith as a living idea in the Monk's mind; in either case, it has a short shelf-life.

Adams's phrase "twenty-four hours was usually about its lot" might perhaps have been clearer if he had worded it as "twenty-four hours was its usual lot"—that is, 24 hours was the typical lifespan of one of the Monk's unshakable (but somehow ultimately discarded) beliefs.

Answer 2

It means as much as one can sensibly manage or sufficient.

Probably derived from either

Collins English Dictionary http://www.collinsdictionary.com/dictionary/english/lot
3. portion in life; destiny; fortune
6. an assigned or apportioned share
but probably closer to this definition (13) which is NOT in Collins online but is listed here http://www.thefreedictionary.com/Lot as belonging to Collins
13. the lot, the entire amount or number

Some quotes

Bare Knuckle Bitch by Marcus Blakeston 2012 Google Books
Just one drink though, and that's my lot. After that it's straight home.

Just for Kicks by Kenny Logan 2009 Google Books
'Another £100,' I said, 'and that's my lot.' James was loads up.

You'll notice both those quotes are my lot and not it's lot but it's the same principle. One could say

My car can just about do a hundred, but that's it's lot.
or with their
I'll give them another thousand dollars, but that's their lot.

So in your original quote about it's lot could be replaced by about as much as the monk could manage.

Answer 3

In the sentence "In practice, the horse knew, twenty-four hours was usually about its lot."; "about its lot" is most likely referring to the horse and the 24 hours the horse has remaining; where remaining may be life expectancy, subject of interest, or the time horse is of use in some unstated context.

Since the horse is not introduced until the final sentence in the presented paragraph there are probably some other sentences which introduce the horse.

All in all this seems to be an example of poet usage.

The introduction statement "In Douglas Adams' Dirk Gently's Holistic Detective Agency, Chapter 2, when talking about how long the Electric Monk believed silly things, the book says:"; hints that the horse may be "how long the...Monk believed in silly things.

Hope this is helpful. 

"..." means for brevity some word or words have been excluded.

This may contain facts, logic and reasoning that may be wrong.