Essentially the soul is pure consciousness and is absolutely non-contaminated and non-material. The liberated souls (Siddhas) are such pure souls. Soul and karma are two distinctly separate categories. One is living being and other is non-living being. But due to the time immemorial, is contamination with matter, the soul's pure non-material form has also become partly material and, therefore, it may further be contaminated. Since embodied-soul is bound with karmas, and karmas are material that is concrete; in spite of being abstract, embodied-soul is concrete also. And because of this, the concrete karmas affect the abstract soul.
वण्ण रस पंच गंधा दो फासा अट्ठ णिच्चया जीवे।
णो संति अमुत्ति तदो ववहारा मुत्ति बंधा दो।।
Vaṇṇa rasa paṅca gaṅdhā do phāsā atṭha ṇiccayā jīve.
No santi amutti tado vavahārā mutti baṅdhā do..
(Acharya Nemi Chandra, Dravya Sangrah, 7)
(Five colors, five tastes, two smells, eight types of touches do not exist in the soul, and from that point of view soul is abstract. The same abstract soul while binds karmas being conditioned by karmic materials becomes to be concrete.)