Learn Italian: Per trovare la sua indipendenza, lo lascio viaggiare da solo. - To find his independence, I let him travel by himself.

In the permissive construction (lasciare + infinitive), the person who is allowed to do the action is the direct object of lasciare. Since "him" is the direct object, we use lo rather than the indirect object pronoun gli.

Could I attach the pronoun lo to the infinitive, like lascio viaggiarlo?

No, you can't attach it to the second verb here. In constructions with lasciare (to let) or fare (to make) plus an infinitive, the pronoun belongs to the main conjugated verb. It must go before it: lo lascio viaggiare.

Why does the sentence start with Per trovare instead of just Trovare to mean "To find"?

When an English sentence uses "to" plus a verb to mean "in order to" or to show the purpose of an action, Italian requires per followed by the infinitive.

Why use da solo instead of just saying solo?

While both translate to "alone," da solo specifically means doing an action "by oneself" or "on one's own" without help. solo is more about the physical or emotional state of being alone. Since this sentence is about finding independence, da solo is the perfect fit.