In the past, learning English as a separate subject seemed relatively easy. The textbook selected and graded items of language which were put into context and then practised intensively. New items were carefully controlled so that the student could cope quite easily. Now that English is used as a medium of instruction, however, all this has changed. Unknown items of grammar and vocabulary appear in texts which attempt to explain new and often difficult information. Difficulties with the language interact with difficulties as regards the subject matter. The student’s reading in his own subject slows down and his comprehension becomes less secure. He expresses himself slowly and often fails to convey his ideas exactly. He is disappointed to find that under pressure he makes a lot of unnecessary mistakes in areas where he knows the correct language forms. His social relations are difficult as he cannot find the right phrase quickly enough to keep a conversation going; so his language often betrays him into dullness, coldness, or worst of all rudeness. Instead of the students being in control of the language, the language seems now to be in control of the student.
All of this can be very depressing and the student can start to feel very anxious. Working in a foreign language is also very tiring, and the concentration and self-discipline required to correct one’s mistakes is very great indeed.

These two factors the altitude and the weather, tend separately and together to defeat the climber. The height weakens, slows him down; it forces him to spend days and nights in the courses of his assault on the summit; the weather, besides adding to the demand of his energy and moral fortitude, conspires to deny him the time he needs to complete his mission. Whereas in lower mountains and on easy ground the weather may be no more than a handicap, in the high Himalayas it is decisive, regardless of terrain.
The deduction to be drawn from these two factors is was clear enough. We must either so fortify ourselves that we could continue, without detriment, to live and have our being above the limit of natural acclimatization, or, better still, we must solve the problem of speed. It was desirable; in fact, that we must meet both these requirements and thus give to those chosen to attempt the summit and to their supporting teams some measures of insurance against the vagaries of the weather, for safety in mountain climbing is as much a matter of swiftness as of sureness of foot. Either or both could be achieved only by the administration of oxygen in sufficient quantities to make up for the deficiency in the air, and for the duration of the upward journey above the limit of successful acclimatization