Laudator Temporis Acti

Alexander Waugh, Fathers and Sons: The Autobiography of a Family (London: Headline, 2004), p. 63, n. 5:

Masturbation was not considered unhealthy until 1710 when John Martens, a quack doctor and pornographer, proclaimed it as such in a book called Onania. Marten's fortune derived from the medicine sold in conjunction with his book. The Church did not consider masturbation a sin, or indeed link it to Onan's behaviour in Genesis, until after the publication of Onania.

Surely this is incorrect. Just in the past few days I noticed the following in Bentley Layton, The Canons of Our Fathers: Monastic Rules of Shenoute (Oxford: Oxford University Press, 2014), p. 93 (rule 6):

Cursed be whoever dares with his own hands to grasp his members for a deed of impurity, that is, defilement.

Id., p. 333, rule 572:

Cursed be whoever touches himself with his own hands in order to do evil deeds.

There are similar prohibitions in medieval penitentials, and cf. Cassian, Conferences 5.11.4 (tr. Edgar C.S. Gibson):

Of fornication there are three sorts ... (2) that which takes place without touching a woman, for which we read that Onan the son of the patriarch Judah was smitten by the Lord; and which is termed by Scripture uncleanness.

fornicationis genera sunt tria ... secundum, quod absque femineo tactu, pro quo Onam patriarchae Iudae filius a Domino percussus legitur, quod in scripturis sanctis immunditia nuncupatur.

Some scholars consider Matthew 5.30 (And if thy right hand offend thee, cut it off) to be a warning against masturbation. See e.g. Will Deming, "Mark 9.42–10.12, Matthew 5.27–32 and b.Nid. 13b: A First Century Discussion of Male Sexuality," New Testament Studies 36 (1990) 130–141, and Andrew R. Angel, "God Talk and Men's Talk: Jesus, Tarfon and Ishmael in Dialogue," in James G. Crossley, ed., Judaism, Jewish Identities and the Gospel Tradition. Essays in Honour of Maurice Casey (2010; rpt. London: Routledge, 2014), pp. 95-117. I haven't seen Giovanni Cappelli, Autoerotismo: Un problema morale nei primi secoli cristiani? (Bologna: Edizioni Dehoniane, 1986).

Diogenes the Cynic viewed masturbation in quite a different light, as a gift of the gods. See:

• A Gift of the Gods
• The Shepherd's Hand