The usage of Infinitive

[Duc]

Hello,
I have just read a composition about the evils of drug addiction.Quote:''...they have a doping effect and hence at the spur of the moment the person may act more vigorously but only to find himself weaker later. ..." I wonder why the verb ''find'' in the sentence is Infinitive but not bare infinitive.Can you explain it to me?
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Don't see your shade think you are great

[Mister Micawber]

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This is an interesting form, duc--which means that I don't know what it is exactly. It is certainly common, and here are some internet examples:

A tribe flees war, only to find uncertainty.

Thieves hit country home - only to find it belongs to policeman

and then in panic he ran blindly through a tunnel only to reach a dead end

The man who struggled to reach the heights only to be thrown down to the depths embodied all of Kafka's aspirations.

Dr. Evil holds the world hostage and demands one million dollars, only to be told that this is a paltry amount in today's economy.

I presume that it is a fixed ('only to...') kind of a nonfinite result clause.
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Native English teacher at Mister Micawber's

[Theresa]

Only to do sth (written)
used to show that sth happened immediately after sth else, especially this is disappointing, surprising.

(Oxford Idioms Dictionary)

[Molly]

This is from the Cambridge Grammar of English (CGE):

Only + to-infinitive

Only is used before a to-infinitive in order to introduce an action or event which is sudden and a little unexpected. This use is usually formal and literary:

The music shop ordered 50 copies of the CD, only to discover that the songs were sung in a foreign language.
He stopped the car, only to start it again violently.
When the Second World War broke out, he tried to enlist, only to be rejected on the grounds of ill-health.