Exegesis:

etherapeusen (3.2, 10; 6.5, 13) ‘he healed,’ ‘he cured,’ ‘he restored’: as the context indicates, both in this passage and elsewhere, the meaning is not that of caring for, or treating a sick person; it means to effect a cure.

pollous kakōs echontas poikilais nosois ‘many who were gravely ill with various diseases.’

kakōs echontas (see v. 32) ‘sick,’ ‘ill.’

poikilais nosois (only here in Mark) ‘with various diseases’: the words are in the dative instrumental case.

kai daimonia polla exebalen ‘and he cast out many demons’: notice that hoi daimonizomenoi ‘the demon-possessed ones’ in v. 32 are the same as the man en pneumati akathartō ‘in an unclean spirit’ of vv. 23, 26. No distinction is drawn between ‘the unclean spirits’ and ‘the demons’; they are the same.

ekballō (cf. 1.12) ‘cast out,’ ‘drive out,’ i.e. cast out the demon, or spirit, from the person possessed by it.

hoti ‘because’: here it is causative, not declarative (as Le Nouveau Testament. Version Synodale translates it).

ēdeisan auton ‘they knew him’: the demons recognized Jesus himself and knew who he was, not merely what was his mission (Lagrange).

Translation:

Sick with various diseases is not to be understood that the same people had numerous different diseases. The sense is distributive, many people and different diseases.

Cast out … demons is an expression which must in many instances be adapted to the local psychological viewpoint. For example, in one instance a native speaker asked, “How could Jesus ‘throw out’ the demons? Was he inside the man in order to do it?” Obviously, the translation in that language had failed to take into consideration the appropriate manner in which one must speak of the process of healing demon-possessed persons. In many languages one must say ‘to cause to come out’ (More), in others ‘take out demons’ (Huautla Mazatec), ‘drove many evil spirits from behind them’ (Kpelle, Loma (Liberia)).

The same verb for ‘know’ employed in verse 24 should be used here.

Quoted with permission from Bratcher, Robert G. and Nida, Eugene A. A Handbook on the Gospel of Mark. (UBS Handbook Series). New York: UBS, 1961. For this and other handbooks for translators see here .