That sort of instruction which is acquired by inculcating an important moral truth, &c.
This expression includes two persons, one acquiring, and one inculcating; and the scene is changed without necessity. To avoid this blemish, the thought may be expressed thus:
That sort of instruction which is afforded by inculcating, &c.
The bad effect of this change of person is remarkable in the following passage.
The Britains, daily harassed by cruel inroads from the Picts, were forced to call in the Saxons for their defence, who consequently reduced the greatest part of the island to their own power, drove the Britains into the most remote and mountainous parts, and the rest of the country, in customs, religion, and language, became wholly Saxons.
Letter to the Lord High Treasurer. Swift.
The following example is a change from subject to persons.
This prostitution of praise is not only a deceit upon the gross of mankind, who take their notion of characters from the learned; but also the better sort must by this means lose some part at least of that desire of fame which is the incentive to generous actions, when they find it promiscuously bestowed on the meritorious and undeserving.
Guardian, Nº 4.
Even so slight a change as to vary the construction in the same period, is unpleasant: