A man walking and concentrating accidentally stepped on a viper which bit him.
Concentrate on one thing to the exclusion of others at your own peril.
[These versions are similar enough to be included on the same page.]
A fowler, taking his bird-lime and his twigs, went out to catch birds. Seeing a thrush sitting upon a tree, he wished to take it, and fitting his twigs to a proper length, watched intently, having his whole thoughts directed towards the sky. While thus looking upwards, he unknowingly trod upon a Viper asleep just before his feet. The Viper, turning about, stung him, and falling into a swoon, the man said to himself, “Woe is me! that while I purposed to hunt another, I am myself fallen unawares into the snares of death.”
JBR Collection (The Fowler and The Ring-Dove)
A Fowler, seeing a Ring-Dove among the branches of an oak, put his piece to his shoulder and aimed at the bird. Just then an Adder, on which unknowingly he had trodden, bit him in the leg. Feeling the poison spreading in his veins, he threw down his gun, and exclaimed, “Fate has justly brought destruction on me while I was contriving the death of another!”
L’Estrange version (A Fowler and A Pigeon)
As a country fellow was making a shoot at a pigeon, he trod upon a snake that bit him by the leg. The surprize startled him, and away flew the bird.
We are to distinguish betwixt the benefits of good will, and those of providence: for the latter are immediately from heaven, where no human intention intervenes.
Vipera et Auceps
Venator quidam, sumpto visco et harundinibus, venatum exiit. Cum autem turdum procera in arbore considentem vidisset, calamis inter se in longitudinem iunctis, oculos ad eum levabat, ipsum capere exoptans. Interim vero contigit ut viperam, sub pedibus iacentem, nescius premeret. Quae cum exasperata ipsum mormordisset, iamiam ille deficiens, “Me miserum,” inquit, “qui cum alium venari vellem, ab alio ad mortem raptus sum.”