'Flesh' in the Bible

The fool is clasping his hands, and eating his own flesh:

Suffer not thy mouth to cause thy flesh to sin, nor say before the messenger, that 'it is an error,' why is God wroth because of thy voice, and hath destroyed the work of thy hands?

And turn aside anger from thy heart, And cause evil to pass from thy flesh, For the childhood and the age are vanity!

And further, from these, my son, be warned; the making of many books hath no end, and much study is a weariness of the flesh.