Thus, through the 'conversion of the basis' one may be called a `destroyer
of defilements' (prahinaklesa). Vasubandhu also goes on to argue that upon
realisation of the supreme goal of yogic attainment (nirodha-samapatti), an
untainted stream of consciousness (nirmala santati) is produced:

For the one who has returned from the Path of Vision (darsana-marga), as a
result of destroying all of the defilements that can be destroyed by
Vision, without remainder, there occurs a fresh stream [of consciousness]
that is without blemish and characterized by revulsion of the physical
basis [9].

The idea of a `conversion of the basis' asraya-paravrtti), that is a
purification of consciousness through the eradication of all defilement
(klesa), becomes an important theme in the subsequent development of the
Yogacara school. The classical formulations of Asanga and Vasubandhu tend
to portray this conversion as a destruction of an essentially phenomenal
store-consciousness (alayavijnana), the repository of karmic seeds (bija).
However, later interpretations within the Yogacara (for example the work of
Paramartha) envisaged this transformation as an eradication of defilements
which leaves behind an essentially undefiled consciousness (amala-vijnana).
This pure consciousness was seen as the foundation or support (asraya)
which originally formed the basis for the activities of the now defunct
defilements. On this view, the conversion of the basis no longer means the
cessation of the store-consciousness, but rather its transformation and
re-turn (paravrtti) to its former pristine condition. This 'pure mind'
tradition within Yogacara Buddhism has clear antecedents in early Buddhism
[10] and is perhaps best represented in the early Yogacara literature by
such texts as the Mahayanasutralamkara. As such it reflects not only the
open-endedness (ambivalence?) of many Yogacara terms, but also the
assimilation of ideas usually associated with the Mahayana notion of
tathagatagarbha [11]. The Abbidharmakosa-bhasya thus provides interesting
source-material for all of these subsequent Yogacara developments.

Taking the argument one step further one might wish to argue that the
notion of the alayavijnana, as utilised by Vasubandhu the Yogacarin, is
little more than an elaboration of concepts already expounded in the
Abhidharmakosa-bhasya, which of course expounds the Dharma from a
Sautrantika perspective. This view, in fact, is propounded by Asanga in
Mahayanasamgraha I. 11 where he argues that the notion of the alayavijnana
far from being a Mahayana innovation 'is mentioned in the sravakayana by
means of various synonyms (paryaya)'. It is tempting to point to the
Theravada notion of bhavanga-citta as influential in this regard, though
Lambert Schmithausen argues that this is unlikely precisely because it is
not mentioned by Asanga at this point [12]. Nevertheless, Rupert Gethin is
surely right to suggest that 'these two concepts are to be understood as
having a certain affinity and that they belong to the same complex of ideas
within the history of Buddhist thought' [13].

In the Abbidharmakosabhasya Vasubandhu asks,

ko 'yam bijabhavo nama atmabhavasya klesaja klesotpadanasaktih

And what is called the seed state? It is the power to originate defilement,
produced by the defilement of one who has attained existence [14].

This characterisation conforms to the early Yogacara conception of the
alayavijnana as sarva-bijaka-vijnana, the store of (defiled) karmic seeds.
Schmithausen offers a list of twenty uses which the concept of alayavijnana
provided (14 'philosophical' and 6 exegetical) for the early Yogacarins
[15]. Most of these cluster around the explanation of personal continuity
given the absence of an abiding-self, and providing a link between karmic
action and subsequent fruition. The Sautrantika metaphor of the seed (bija)
became central in the case of the latter issue once the Vaibhasika
conception of the existence of dharmas in past, present and future (the
sarvastivada position) was rejected. However, as Schmithausen points out,
although the Sautrantika postulated the notion of a karmic seed to
establish causal continuity over time, the Yogacara seems to have felt that
this required the further postulation of a store (alaya) consciousness as
the repository of these seeds. Nevertheless, it is important to note at
this point that the store-consciousness is by no means considered to be an
ultimate reality in the works of either Vasubandhu the Yogacarin or Asanga,
as has sometimes been suggested. In the Viniscayasamgrahani section of the
Yogacarabhumi, Asanga describes the alayavijnana as the root of defilements
(samklesamula) which ceases through the cultivation of wholesome dharmas
[16]. Equally, in Trimsika v.18 Vasubandhu suggests that the alayavijnana