After the verb yam 'to strive', preceded by sam , ut and āṅ , when it does not refer to a book, the ātmanepada is used, when the fruit of the action accrues to the agent.,
The phrase 'when the fruit of the action accrues to the agent' is read into this aphorism by anuvritti from sutra 1.3.72. As ब्रीहीन् संयच्छते 'he gathers rice'; भारमुद्यच्छते 'he lifts up the load'; वस्त्रमायच्छते 'he draws out the cloth.' The root yam preceded by the preposition आङ् takes the terminations of the Atmanepada by virtue of aphorism 1.3.28 ante; but in that aphorism the verb was intransitive, here it is transitive, and this explains the necessity of making two different sutras for one compound verb आयम्.
Why do we say 'when it does not refer to a book.' For otherwise the verb will take the terminations of the parasmaipada. As उद्यच्छति चिकित्सां वैद्यः 'the physician diligently studies medicine.'
When however the fruit of the action does not accrue to the agent, the above compound verbs are parasmaipadi. As संयच्छति, उद्यच्छति, आयच्छति.,