(Gakumon ni oudou nashi; “There is no royal road in learning”)
There is no easy way, no quick fix or magic bullet, for mastering a field of study. You need to acquire information and mental tools, incorporate them into your worldview, and practice their use. While this is true in any language and culture, it is especially so in Japanese, where even mundane literacy requires hundreds or thousands of hours of practice. Alternately, there is an order in which certain subjects must be studied; there is no way to skip parts of that sequence and still learn effectively.
学 (gaku) is “study” and 問 (mon) is “question”; put them together and you get “study,” “scholarship.” This noun is followed by に (ni), a positional/directional particle, in this case acting equivalently to the English “in.” Then comes another noun: 王 (ou) is “king” and 道 (dou) is “road”; combined they make “royal road.” The term can mean “kingship,” “righteous rule,” or “noble path” – or “shortcut,” “easy method.” This is modified, without particles, by the negating adjective 無し in its sentence-final form. Despite this kotowaza‘s simplicity, which may make it feel truncated, it functions as a complete sentence as written.
Apparently this saying is derived from the story of the first Ptolemy asking Euclid to present him with a simpler guide to geometry than his Elements, to which Euclid supposedly replied “There is no royal road to geometry.” We see, first, that Euclid would be absolutely blown away by modern textbooks (and the fact that geometry is routinely taught to teenagers), and second, that the Japanese version has expanded its scope from one branch of mathematics to all of academia. (Keep in mind, however, that physical skills or other non-academic areas of “learning” still fall outside of its scope.)
One can also use the more literal 近道 (chikamichi, “shortcut”) in place of the figurative 王道.
(“Sekibungaku wo mi ni tsukeru ni wa, mazu ha daisuugaku to sankakuhou, sore kara bibungaku wo manabu to iu junjo wo fumanakya ikemasen yo. Gakumon ni oudou nashi da shi.”)
[“If you want to master integral calculus, you need to learn first algebra and trigonometry, then differential calculus, in order. There are no shortcuts in learning.”]