0. The fate of OCS borrowings into Russian has generated a substantial literature, without however tracing in much detail the processes by which the genetically South Slavic forms were incorporated into the various genres of written Russian as these developed across time. The present study examines the distribution of SS az and ES ja in the autobiography of the 17th-c. Archpriest Avvakum. The distribution depends both on phono-syntactic environments and on the part of the text in which they occur (B[eginning], M[iddle], E[nd]).
1.1. Sentence-initial position shows roughly equal use of az (46): ja (48) while clause-initial position prefers the ES form: az (5): ja (11), i.e., pronoun choice is conditioned by the strength of the juncture on which it lies.
1.2. This is even clearer in non-initial position, where VS order shows az (5): ja (21), interpretable as amild hiatus deletion, as contrasted with postconjunctional position after a, i where the proportion is az (10): ja (128), i.e., strong hiatus deletion; this distribution represents a further development of the situation in the 1377 laurentian chronicle, as described elsewhere.
2.1. Across the text, B and E show similarities such as preference for initial az over initial ja (15:7 in B, 35:22 in E), contrasting with M, which strongly prefers the ES form: az (4): ja (34).
2.2. B and E also show a mirror difference: B has most of the SS forms in its first half (interpretable as incipital function), while E has most of its in its second half, e.e. interpretable as closural function.
3.1. The choice between SS az and ES ja is thus conditioned both by the latter's hiatus-deletion function on minor boundaries and by the text-level distinction of marked incipital and closural position (with az) as contrasted with straight na ja).
3.2. These conclusions are suggested but not proven by the data, and therefore must be considered only tentative.