Question on yena/tena structure

Dear Friends,

Is anyone familiar with the yena/tena structure whereby  the subject approached with the verb upasaṃkamati is in the nominative, instead of the accusative?

A typical instance is at the beginning of the Mahāparinibbāna sūtta where Ajātasattu tells his minister Vāsakāra to

ehi tvaṃ brāhmaṇa yena bhagavā ten(a)upasaṃkama

"Go Brahmin, approach the Buddha".

ehi is imperative and so is upasaṃkama. One would expect an accusative here (bhagavantaṃ).


Warder mentions this structure on page 14, without explaining its origin or use as does Collins on page 25. Apparently the person approached is in the nominative and the person doing the approaching is also in the nominative (tvaṃ)   with the verb being in the active (not passive, as one would expect) form.


Another, even simpler example, at the beginning of the Mahānidāna sutta:

atha kho āyasmā ānando yena bhagavā tenupasaṅkami,...


"Ven. Ānanda approached the Blessed One..."

Exactly what function the yena/tena relative/correlative structure performs, I am not sure, unless is was a hold-over from the passive (yena bhagavā upasaṅkami, tena Ānanda...) with upasaṅkami a passive aorist (if such a form exists in Pāli).


Any suggetions as to how this structure originated or what the yena/tena means or is used for would be appreciated. Why don't we just say āyasmā ānando bhagavantam upasaṅkami...?

Mettā

Bryan

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