Iron rusts from disuse; water loses its purity from stagnation... even so does inaction sap the vigor of the mind.
The European mind is capitulating. It is capitulating out of weakness, out of [intellectual] sloth, out of apathy, out of lack of imagination
We are lazier in our minds than in our bodies.
Perhaps there are none more lazy, or more truly ignorant, than your everlasting readers.
Indolence is the sleep of the mind.
The inert mind is a greater danger than the inert body, for it overlays and stifles the desire to live.
Idleness is the stupidity of the body, and stupidity is the idleness of the mind.
We have wasted our spirit in the regions of the abstract and general just as the monks let it wither in the world of prayer and contemplation.
Sedentary people are apt to have sluggish minds. A sluggish mind is apt to be reflected in flabbiness of body and in a dullness of expression that invites no interest and gets none.
A lazy frost, a numbness of the mind.
Mental effort, I would argue, is relatively rare. Most of the time we coast.
Where no interest is takes in science, literature and liberal pursuits, mere facts and insignificant criticisms necessarily become the themes of discourse; and minds, strangers alike to activity and meditation, become so limited as to render all intercourse with them at once tasteless and oppressive.
No one can be as intellectually slothful as a really smart person
There are lazy minds as well as lazy bodies.
[He is] too used to borrowing brains instead of using his own.
Referring to Nelson Rockefeller and his practice of surrounding himself with brilliant staff members:
The study of books is a drowsy and feeble exercise which does not warm you up.