I was talking the other day about incorrupt saints with my (non-religious) family. They were duly impressed with the phenomenon of which they had not previously heard.

For some reason I had been giving some thought to the Incorruptibles, having mentioned to JHW, my editor, my observation that it seems that many of the saints who remain incorrupt after death were those who had enjoyed visions of Our Lady, most prominent of whom, of course is St. Bernadette.

Today, I was just glancing over Daniel Mitsui's blog, (always a rewarding experience), and saw this:

Summa theologica 51.3
It was not fitting for Christ's body to putrefy, or in any way be reduced to dust, since the putrefaction of any body comes of that body's infirmity of nature, which can no longer hold the body together. But as was said above, Christ's death ought not to come from weakness of nature, lest it might not be believed to be voluntary: and therefore He willed to die, not from sickness, but from suffering inflicted on Him, to which He gave Himself up willingly. And therefore, lest His death might be ascribed to infirmity of nature, Christ did not wish His body to putrefy in any way or dissolve no matter how; but for the manifestation of His divine power He willed that His body should continue incorrupt. Hence Chrysostom says that with other men, especially with such as have wrought strenuously, their deeds shine forth in their lifetime; but as soon as they die, their deeds go with them. But it is quite the contrary with Christ: because previous to the cross all is sadness and weakness, but as soon as He is crucified, everything comes to light, in order that you may learn it was not an ordinary man that was crucified.

Since Christ was not subject to sin, neither was He prone to die or to return to dust. Yet of His own will He endured death for our salvation, for the reasons alleged above. But had His body putrefied or dissolved, this fact would have been detrimental to man's salvation, for it would not have seemed credible that the divine power was in Him. Hence it is on His behalf that it is written: What profit is there in my blood, whilst I go down to corruption? as if He were to say: If My body corrupt, the profit of the blood shed will be lost.

Christ's body was a subject of corruption according to the condition of its passible nature, but not as to the deserving cause of putrefaction, which is sin: but the divine power preserved Christ's body from putrefying, just as it raised it up from death.

From which maybe we can extrapolate some kind of explanation for the extraordinary phenomenon of incorrupt saints.

A saint is someone who has become the most Christ-like of people. If their extraordinary sanctity can do things like create a likeness in their lives to the point of showing the marks of Christ's Passion on their bodies, and in phenomena like bilocation, levitation etc, it would stand to reason that this likeness would be carried on after their deaths, especially if it could be a means of convincing unbelievers.

I am going to keep thinking about it.