Finals are coming up!
(Ichinen iwa wo mo toosu;
“Single-mindedness pierces even a boulder.”)
No matter what obstacles you are faced with, sufficiently determined effort will allow you to overcome them, just as even a barrier of stone can be broken through or overcome when enough force is applied.
一 (ichi) is “one,” and 念 (nen) is “thought,” “feeling,” “desire,” “idea.” By their powers combined they become 一念, “a single thought” or “determination.” 岩 (iwa) is a large rock or boulder; alternately a cliff or even an anchor, although here the first meaning is at play. を (wo) is our object-marker particle, while も (mo), often translated as “and,” is acting as an intensifier: in this usage its meaning is something like “even” or “a whole.”
通す (toosu) is our verb; it has a long list of possible translations, but the overall gist is something like “to push something through,” “to go all the way through.” Note that the verb seems to be taking a causative (and sentence-final) form here, but that the effect is to cause the stone to be passed through, rather than causing the stone to pass through anything else. Keep in mind that passive and causative verbs can have different behavior in Japanese than they do in English.
The origin story for this one is fascinating. Supposedly Li Guang mistook a large stone for a tiger crouching in the tall grass and fired and arrow at it. His prowess in archery was such that the arrow pierced the stone. This saying is thus based on an older version, 石に立つ矢 (ishi ni tatsu ya, “an arrow standing in a stone”). It is possible, although not certain, that the saying was altered and the Buddhist concept of 一念 added later to aid the spread of Buddhist teachings in Japan. There are a number of other sayings with related meanings, including the previously-treated 雨垂れ石をうがつ.
Although the base kanji characters involved have different meanings, in this case 通す can be replaced by 徹す without any change in meaning or pronunciation.
(“Ichinen iwa wo mo toosu da to omotte, zettai seikou shite miseru to dangen shita.”)
[“Thinking that single-minded determination could overcome any obstacle, I declared to them that I would definitely succeed.”]