Can you explain the concept of the 'Unmanifest' or 'Avyakruta' as described in the source material?

The source material from Chapter 50 describes the 'Unmanifest' (Avyakruta) as the 'causal' (karana) body of the soul. It is characterized as being with the reflection of consciousness and is considered the cause of pure ignorance. The text also refers to it as 'Unevolved.' Its nature is paradoxical, as it is described as being neither with parts nor without parts, nor a combination of both. The ignorance of the Soul is identified as the very cause of this Unmanifest body, and its removal is essential for attaining liberation through the knowledge of Brahman.