@use of fourth

The fourth ending means "to"; it may be used with verbs of throwing, aiming and giving, by caturthIsampr..., to express the receiver of those verbs —

trizirase zailaJ cikSepa त्रिशिरसे शैलं चिक्षेप "threw rock to triziras"

brAhmaNAya gAn dadAti ब्राह्मणाय गां ददाति "gives cow to brahmin"

The fourth ending is rarely used, because with verbs of giving the sixth is more common —

brAhmaNasya gAn dadAmi ब्राह्मणस्य गां ददामि I give a cow to the brahmin.

Also to express "point of view", the sixth is used, not the fourth —

pipIlikAnAG girir eSaH पिपीलिकानां गिरिरेषः "For ants, this is a mountain."

However the fourth must be used compulsorily with **namas- नमस्,

namo gaNapataye नमो गणपतये "salutation to gaNapati"

and also when meaning result, purpose, motive. The fourth may express those senses by a /vArttika to caturthIsampr... —

pRRSaG gacchAmi sAgarasya darzanAya पॄषं गच्छामि सागरस्य दर्शनाय "i'm going to Perth in order to see the sea"
tatra vadhAya gacchati तत्र वधाय गच्छति "goes there in order to kill"

A word with fourth ending can be used predicatively, with the meaning of "is for", "aims to", "is done in order to", "results in", "leads to". This is very disconcerting when you are not yet used to it —

kAmakrodhau hi bandhAya vimokSAya tv asaGgatA ||
कामक्रोधौ हि बन्धाय विमोक्षाय त्वसङ्गता ॥
"because desire and anger lead to bondage, attachmentlessness leads to liberation"