For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a horseshoe nail.
(First notice of it it in the 14th century)
Well, I was thinking of this today in the 21st century, nothing to do with horses or losing a battle, but for want of something I need (a password, a recognition of my login -so, two things) I can't get information I need to finish my GST - NOT HST and oh,, how I resent our government's tax on reading! I''l link about it tomorrow, and make do with the Jays' game - - aargh! Not a comforting substitute.
Well, some days are not satisfying, nothing wrong with them, not disasters, but....not good. Not complaining, and the image of the missing nail led me to a whole plethora of aphorisms, proverbs, cautionary tales, warning people to consider the consequences of seemingly innocent errors or lacks. Look before you leap, I copied the list, haven't checked it. Let's see if unchecked leaps are in there....
There are a number of other metaphors and expressions which refer to small changes leading to chains of events with undesirable or unexpected consequences, differing in nuances.
- Creeping normality
- Foot in the door – a persuasion technique
- Slippery slope – an argument, sometimes fallacious
- "The thin end of the wedge"
- Domino effect
- For Want of a Nail – the claim that large consequences may follow from inattention to small details
- Boiling frog – the notion that gradual change tends to go unnoticed until it is too late – often discussed by drawing an analogy to a false story about what will allegedly happen to a frog in gradually warmed water
- "Give them an inch; they'll take a mile." The original saying goes "Give them an inch, and they'll take an ell."
- In Chinese culture, the "inch-mile" saying corresponds to the chengyu (four-character expression) délǒng-wàngshǔ (得隴望蜀), which is a quotation from the Book of Later Han about a Chinese general who took over Long (now Gansu) only to pursue further southwards into Shu (now Sichuan). Another more similar corresponding chengyu is dé cùn jìn chǐ (得寸進尺), meaning "Gain an inch and ask for a yard." 
- In Russian culture a similar phrase sounds, literally translated, as "offer him a finger, and he will bite a hand off up to the elbow".
- In Finnish, there is the expression Jos antaa pirulle pikkusormen, se vie koko käden ("If you offer the devil [even just] a little finger, it takes the whole hand/arm").
- In German, there is the expression "Gib jemandem den kleinen Finger, und er nimmt die ganze Hand" ("If you give somebody the little finger, he will take your whole hand").
- In Dutch, there is the expression "als je hem een vinger geeft, neemt hij de hele hand" ("If you give him a finger, he will take your whole hand").
- In Portuguese, the correspondent to this idiom is "Você dá uma mão, e eles querem o braço inteiro" ("You lend a hand, and they want the whole arm").
- In Greek, a similar expression is: 'Δώσε θάρρος στον χωριάτη να σ'ανέβει στο κρεβάτι' ("Give the peasant freedom, and he will hop on your bed")
And so it goes.
And then there's the camel's nose.
Back to the Jays game. :-(