One of the most striking aspects of the Commandments of the Reformed Decalogue was the sheer range of actions which they came to be seen to enjoin or prohibit. However, this tendency to expand the commandments from the specific action forbidden (or exhorted) in the text to spiritual and temporal acts, in thought, word and deed, and to other similar types of offence, had impeccable biblical credentials. Christ himself, in Matthew 5:21-22, had explained:
Ye have heard that it was said of them of old time, Thou shalt not kill; and whosoever shall kill shall be in danger of the judgement: But I say unto you, That whosoever is angry with his brother shall be in danger of the judgement: and whosoever shall say to his brother, Raca, shall be in danger of the council: but whoseoever shall say, Thou fool, shall be in danger of hell fire.
The four short monosyllables of the Sixth Commandment – thou shalt not kill – were therefore stretched and twisted by expositors of the Decalogue into some quite astonishingly intricate patterns, which reflected the religious and moral climate of the day. The godly vicar of Ryton, Francis Bunny, explained that the commandment forbade killing with hand, heart and tongue, ‘and all the things that tend to the hurt of any mans person’, including bereaving him, spoiling his goods and possessions, or omitting ‘such duties, as tend to the safety or good of other men’. This was a totalising portrait of how to live one’s life with the utmost care for the lives of others.
Crimes of the heart were deemed by Bunny to include anger, hate, and envy, for ‘the envious heart is a murdering heart’. Murderous plots did not need to succeed for the perpetrators to be guilty of sinning against the Sixth Commandment. ‘And in this sort’, Bunny remarked, ‘no doubt many of our Romish-Catholicks, who knew in general that mischief was intended on the 5. of November, when that most inhumane and savage purpose that ever was thought upon, should have been executed, and wished in their hearts it might take effect, are cruell and monstrous murderers’.
Bunny was somewhat unusual in the extent to which he dwelt on theft in the Sixth Commandment (given that ‘Thou Shalt Not Steal’ was the next precept but one in the sequence!). Still, his reasoning was sound: thieves were breakers of the commandment because robbery made man’s life bitter and unpleasant, a crime of which usurers, oppressors of the poor and cruel masters of servants were also guilty.
The commandment extended to filthy and reproachful speeches, as well as slanders: ‘the slandering tongue be a murthering tongue’, explained Bunny, ‘in that it taketh away a mans reputation, which is as it were the life of a mans name’. Still, while malicious slandering was forbidden, the Christian man was obliged to reprove sin and lewd living in others – Christian reprehension was ‘much commended by Christ and his Apostles’.
The Sixth Commandment also required specific duties of those holding particular offices. It enjoined ministers to admonish the people of the dangers of living a sinful life, and obliged parents to bring their children up in the knowledge and fear of God. Magistrates were required ‘by due punishments [to] represse bloodshed and all disorders in the Common wealth’, and the commandment which forbade killing was also seen to require lawful judicial punishment, including execution. In general, the commandment enjoined Christian men and women to feed, water and lodge strangers (although not vagrants or beggars), and to tender care for the safety of their neighbours.
Other authors took things even further. William Whately explained that care for oneself according to the Sixth Commandment necessitated moderate and temperate use of food, apparel, rest and sleep, exercise, and ‘even sometimes also nuptial society of generation and the like’. In contrast, sins such as gluttony and sloth were forbidden as forms of self-harm. William Perkins even saw comprehended under the same commandment the duty, as outlined by Deuteronomy 22:6,
If thou finde a birds nest in the way, in any tree, or on the ground, whether they be young, or egges, and the damme sitting vpon the young, or upon the egges, thou shalt not take the damme with the young, but shalt in any wise let the damme goe, and take the yong to thee, that thou maist prosper and prolong thy daies.
By any stretch of the imagination, this was some distance from the literal sense of ‘thou shalt not kill’…
 Francis Bunny, A guide vnto godlinesse: or, A plaine and familiar explanation of the ten commandements, by questions and answeres fittest for the instruction of the simple and ignorant people (1617), STC2: 4100, pp. 170-187.
 William Whately, A pithie, short, and methodicall opening of the Ten commandements (1622), STC2: 25315, pp. 143-4.
 William Perkins, A golden chaine: or The description of theologie containing the order of the causes of saluation and damnation, according to Gods word (1600), STC2: 19646, p. 74.